Vol. 25. N o. 191 Se p t. 1939.
COMPARATIVE OPERATING COSTS OF PETROL AND COMPRESSION IGNITION ENGINED BUSES FOR PASSENGER TRANSPORT.*
By W. C.
W h a l l e y , !A .M .Inst.T .
Sy n o p s i s.
I n th is paper on th e o p eratin g co sts of oil- a n d p e tro l-en g in e d o m n ib u B k the au th o r has em phasized th e fa c t t h a t th e m a in in c e n tiv e to th e use alternative fuels or types of prim e m o v er is econom y in o p e ra tio n c o m b in e d ^ w ith ease of handling of th e fuel. T h e ra p id p rogress m ad e b y th e oil engine in the last decade is shown to be due to th e e x ce lle n t m a n n e r in w h ich it fulfils these requirem ents.
The saving on a 56-seater double-deck b u s is s ta te d to b e 1 T 52d. p e r bus mile, or £216 per annum on an n u al, m ileage of 45,000 m iles. T h is is a n e tt saving after m aking due allowance for a d d itio n a l o v e rh ea d a n d m a in te n a n c e charges.
The difficulty of M unicipal u n d e rta k in g s in d e alin g w ith p e a k lo ad s a n d the effect of ta x a tio n is illu stra te d g rap h ically , a n d th e su m m a ry of replies to a questionnaire by tw en ty -six u n d e rta k in g s show s t h a t a lth o u g h th e conditions v ary greatly in different tow ns, th e re is am p le ev id en ce of th e preference for th e oil-engine vehicle.
Finally, th e a u th o r does n o t c o n te n d t h a t th e p re se n t oil engine h a s reached finality, an d m entions ex p erim e n ts w hich are now being m ad e w ith the injection of gas an d th e a lte rn a tiv e use of p ro d u c er gas, a lth o u g h it m ust be rem em bered th a t a n y a lte rn a tiv e m u s t c o m p ly w ith th e re q u ire ments already em phasized, of econom y in o p e ratio n a n d ease of sto ra g e a n d handling of th e fuel.
I
npreparing this paper, I realized th a t it w ould n o t be sufficient to present figures based solely on th e operation o f m o to r om nibuses in a n y one city. I therefore drew up a Q uestionnaire w hich was sen t to th e General Managers of tw enty-six undertakings in G reat B ritain , an d I am grateful to them for th e care w ith which th e y have com pleted th e Ques
tionnaire, and it is on th e experience of these various m unicipalities t h a t I have based my figures.
Among the m any varied item s which go to m ake th e to ta l cost of op era
tion of a passenger-transport service, th e fuel bill is one of th e highest.
In Manchester, th e cost of petrol represents 21 \ per cent, o f th e to ta l running cost of th e petrol vehicle, and w ith th e com pression-ignition engine the fuel cost is equal to 14 per cent. F u rth e r, m an y o f th e o th er items, such as loan charges, licence costs, an d th e p a y m e n t o f wages—
rigorously controlled by th e T rade U nion A greem ents— can only be reduced by running greater mileages per vehicle, which in large cities w ith high peak loads is sometimes very difficult. The c h a rt in A ppendix No. 1 shows very clearly th e morning an d evening peak loads, an d it w ill be noticed th a t 60 per cent, of th e licensed buses are in use for only a com paratively short tim e in the m orning an d evening.
The fuel costs, as I have pointed out, represent high percentages o f th e working expenses, and th ey therefore present an a ttra c tiv e field to th e operating engineer in search of econom y. These high percentages are,
An , Perc Presented for discussion a t th e M orning Session, 23rd M ay, a t th e S u m m er 1 + n u - e s tltu te P e tro le u m h e ld in B irm in g h a m , 2 2 -2 4 th M ay, 1939.T Kolhng Stock S u p e rin te n d en t, M a n ch ester C o rp o ra tio n T ra n s p o rt D e p a r tm e n t.
WHALLEY : COMPAEATIVE OPERATING COSTS OF
of course, due to taxation. W hen one considers th a t th e n e tt price of fuel oil for instance, is something under 4d. per gallon, one gallon of which is sufficient to propel a double-deck vehicle 8 | m iles, it represents a re
markable achievem ent on th e p a rt of th e Oil Refiners an d D istributors th at it can be refined, im ported, and d istrib u ted all over th e country to con
sumers a t a price which, b u t for tax atio n , would be approxim ately 4d. per gallon. We have, however, to deal w ith things as th e y are, and as taxation a t present increases th e price of petrol by som ething like 216 per cent, and fuel oil by approxim ately 232 per cent., th e need for economy in fuel consumption becomes apparent. The im portance o f th is m ay be judged by the following :—
An extra quarter of a mile per gallon to th e owner-driver of a private car m ay to him appear a m a tte r of no g reat im portance. Let us, however, see w hat this apparently very sm all econom y means to the P.S.V. operator. In M anchester during th e financial year which closed on 31st March last, over 26,000,000 bus-m iles were run, th e consumption of petrol being 847,000 gallons and o f fuel oil 2,615,000 gallons. If the average m.p.g. could have been raised b y ju s t th is q u a rte r of a mile per gallon, the resultant economy in fuel w ould have reduced th e working expenses by £6685. W ithin th e n e x t tw o or th ree years this annual mileage m ay be alm ost doubled, so it will be seen t h a t w hen I said fuel presents an attractiv e field for th e engineer in search o f economy, maybe I should have said th a t economy in fuel consum ption is a m a tte r of para
m ount importance, provided th a t economy in th e one direction is not more than cancelled out by heavier expenses in another.
In the years following th e W ar m an y experim ents were made with alternative fuels to petrol—paraffin oil and m ixtures of petrol and paraffin oil being tried w ithout great success. T he n e x t stage was the use of a creosote distillate in an ordinary spark-ignition p etrol engine, the engine being started on petrol and then ru n on th e creosote fuel when warmed up.
I t was found necessary w ith these engines to increase th e compression ratio to 6 to 1 and to fit special heating a p p a ra tu s to th e induction pipe.
In order to vaporize th e creosote, th e in let m anifold was to tally enclosed in the exhaust m anifold, th e la tte r being p ro tected by a shield from the cooling-draught caused by th e fan. W ith such a design there was very little control of the heating of th e inlet m anifold, th e tem perature of which had a m ost im portant bearing on th e running of th e engine. I f too cold, a rapid deposition of carbon took place in th e m anifold and round the valve, which ultim ately caused th ro ttlin g of th e gases. I f too hot, cracking of the creosote oil took place, causing deposition of carbon compounds in the cylinder, which ultim ately reached and contam in ated th e sump oil. Over
heating of the inlet gases also caused a drop in th e volum etric efficiency of the engine. G reat care was also required in th e setting of th e controls, in order to get a satisfactory change-over from p etrol to creosote.
The lubrication of th e engine presented certain difficulties, owing to
dilution and contam ination caused by th e creosote and asphaltic compounds
formed during combustion. Castor oil was used w ith success owing to its
property, not so much of dissolving th e com pounds m entioned above, as of
keeping them in suspension and p reventing th em separating out and
causing sludging. The high cost of castor oil, however, made its use
PETROL AND COMPRESSION IGNITION ENG INED BU SE S. 5 7 5
uneconomical, and certain m ineral oils were used w ith fair results. In service the engine “ pulled ” well, b u t occasional oiling up o f plugs took place. I t was necessary to have th e engine thoroughly w arm ed up before leaving the garage. To facilitate starting, th e engine had to be allowed to idle on petrol for a short tim e before sh u ttin g dow n a t night, in order to clear the cylinders of th e products o f creosote com bustion w hich caused gumming up of th e pistons. D ue to th e carboning up o f th e cylinders, frequent docking was required, and general running m aintenance was ra th e r higher than for a petrol engine. O verhaul costs also ten d ed to be higher.
The following figures show th e results o f th e running of a double-deck vehicle operating on a route w ith freq u en t stops an d equipped w ith a petrol engine modified for
ru n n in gon creosote. C astor oil was n o t used as a lubricant, but a special m ineral oil a t la. 8d. per gallon, which gave fairly good results :—
Miles.
P etrol. C reosote. L u b . Oil.
Galls. M .P.G . G alls. M .P .G . G alls. M .P .G .
4279 411 10-4 659 6-5 32J 132
Petrol . . . Is . 1 \ d . p e r gall.
C r e o s o te ... 7| d . n Lubricating o i l ...Is . 8d. „ Cost of fuel an d lu b ricatin g oil . . . 2-595d. p e r m ile.
Cost of petrol for sim ilar p e tro l engine . . . . . 3-176d . „ Cost of lubricating oil for p e tro l engine (200 m .p .g . a t Is . 8d.
per g a l l . ) ...O-lOOd.
Total cost of p e tro l an d lu b ricatin g oil fo r p e tro l engine . 3-276d . ,,
Saving shown b y creosote engine . . . 0-68 Id . „
On an annual mileage of 35,000 th e saving would be ap p ro x im ately £100 per bus per annum. However, m uch difficulty was experienced w ith th e running of the two buses which were fitted, owing to th e im possibility of maintaining a constant tem perature in th e in le t m anifold, due to th e frequent starting and stopping, and th e cost of m aintenance was such th a t the experiment was abandoned afte r ab o u t eighteen m onths.
In 1929 one or two oil-engine chassis were introduced from th e C ontinent, and English m anufacturers began to consider th e fitting of th e so-called diesel engine to commercial vehicles. In 1930 Messrs. Crossley M otors of Manchester, in collaboration w ith Messrs. G ardners o f P a tric ro ft, supplied three oil-engined douhle-deck omnibuses— one fo r Leeds, one for Sheffield, and one for Manchester. These buses were fitted w ith a m arine ty p e of engine adapted to fit in a stan d a rd chassis. The m axim um speed of th e engine was governed to 1300 revolutions per m inute, which gave th e bus a maximum road speed of 28 miles per hour.
The early experim ents w ith these oil engines were so im m ediately
promising th a t operators dem anded more, and th e engine-builders responded
w b eS1^ IUi lg and Producing an engine specially for ro a d -tra n sp o rt work
first tried m axunum speed th a n th e m arine engines which were
At this point it m ay be of in tere st to d irect y our a tte n tio n to a re tu rn
576
WHALLEY : COMPARATIVE OPERATING COSTS OFprepared by Mr. Mackinnon in his paper read a t th e m eeting of the Union Internationale de Tram w ays in 1935 (ex tract below), from which you will see th a t whereas a t 31st May, 1931, th e re were only eleven diesel-engine units in municipal bus service, by 31st Decem ber, 1934, there were no fewer th a n 1144.
D ate.
N u m b e r of M u nicipal U n d e rta k in g s O p e ratin g
D iesel E n g in es.
T o ta l N um ber of D iesel E ngines in
Service.
31st May, 1931 . 31st M arch, 1932
May, 1933 ...
30th S ep t., 1933 . . . . 30th Ju n e , 1934 . . . •
31st Dec., 1934 . . . .
8 14
33 (ap p ro x .) 47
59 72
11 54
214 (approx.) 389
780 1144
The figures a t 30th Ju n e , 1938, for vehicles owned by members of the Municipal and T ransport Association (see A ppendix II) were as follows
Single D eck . D o u b le D eck . T o tal.
P e tro l . . . 1433 1904 3337
Oil . . . . 935 4486 5421
from which you will see th a t o u t of a to ta l o f 8758 single- and double-deck motor omnibuses, no fewer th a n 5421 are o perated by compression-ignition engines.
Dealing with th e whole of th e country, th e figures tak en from the Ministry of T ransport re tu rn (given in A ppendix I I I ) show th a t the maxi
mum num ber of hackney vehicles licensed during th e q u arter ended 30th September, 1938, operated by petrol vehicles o f over eight seats capacity, had fallen by 7539, as com pared w ith th ree years ago, w hilst a t the same time the num ber of similar vehicles driv en b y heav y oil had increased by 11,781, this latte r figure being an increase of 212-62 per cent, on the figure for September 1935. Comparing th is w ith th e goods vehicles, there was a reduction of 3345 in th e “ over 21-ton ” class a n d an increase of 3135 in the heavy-oil vehicles, this la tte r figure being equal to 57-8 per cent, increase over the figure in Septem ber 1935.
Table I I I , Section C, of th e M inistry of T ran sp o rt R eturns for 1938 gives the num ber of vehicles registered for th e first tim e during the twelve months ended Septem ber 1938. Looking a t double-deck passenger vehicles from forty-eight to sixty-four seats, it is noticeable th a t in this year only ninety new petrol-engine buses were licensed, as against 1989 oil-engine buses of th e same capacity. F rom these figures it will be seen th a t as regards large passenger vehicles, th e oil engines now rank supreme.
The position with goods vehicles is scarcely th e same, as, owing to the imposition of the 20-miles-per-hour speed lim it for vehicles weighing over 2| tons, the application of th e oil engine to goods tra n sp o rt has received a setback, it being difficult to keep th e w eight o f th e oil engine sufficiently low to enable the vehicle to qualify for th e high-speed category.
From the foregoing brief historical review it will be seen th a t the com
PETROL AND COMPRESSION IGNITION ENG IN ED BUSES. 5 7 7
pression-ignition engine has firm ly established itself as a prim e m over in municipal passenger tra n sp o rt, an d it is m y purpose to show in this paper th a t th e chief reason for th e ra p id rise in p o p u larity of th e com- pression-ignition engine is th e saving in fuel cost over th e petrol-driven engine.
I now propose to deal w ith th e cost o f o peration u n d er th e following headings : (1) C apital C o s t; (2) O peration an d M aintenance Cost.
( 1 ) Ca p i t a l Co s t.
In the early days o f developm ent of th e high-speed diesel engine the capital cost of a vehicle so fitted was £200-£250 over and above th a t of the corresponding petrol-engine chassis. This is understandable when it is remembered th a t th e engines were b u ilt in sm aller num bers and were distinctly of an experim ental n atu re. T o-day th e additional capital cost of the oil-engine vehicle over th e petrol-engine vehicle is approxim ately
£100 per chassis.
The difference in th e annual charges betw een an oil-engine bus and a similar petrol-engine bus am ounts to £19, based on an estim ated ex tra charge of £100 per chassis. On an annual mileage of 45,000 th is represents 0-lOld. per vehicle-mile.
In th e case o f m unicipal undertakings it is necessary to m ake application to the M inistry o f T ran sp o rt for sanction to borrow th e money upon the security of th e City R a te for th e purchase o f m otor omnibuses, and th e repaym ent of th e loan is spread over a period of eight years, in addition to the paym ent o f in terest on th e m oney borrowed. Experience in M anchester has proved th a t th e life of a m otor bus does not always reach th e full limit of the loan period o f eight years, so additional provision is charged annually in order th a t th e whole capital o u tlay is provided in six-and-a-half years.
. This additional provision is set aside to p ay off th e outstanding d eb t whenever a bus is p rem atu rely tak en o u t of service and scrapped. The additional provision on buses th a t rem ain in service for th e full loan period is thus available for th e purchase of, say, new bodies, or for general renewal purposes (see A ppendix IV).
Some undertakings are in th e fo rtu n a te position of having a reserve fund available so th a t new vehicles m ay be purchased out of accum ulated profits from previous years. I n th is case a sum equal to th e loan d eb t repaym ent could be charged against revenue each year and credited to th e Reserve Fund, so th a t by th e tim e th e vehicles are worn out, th e am ount in th e reserve fund would again be available for buying more vehicles.
Capital costs are g reatly influenced by th e conditions under which th e
vehicles operate. The life o f a bus in M anchester, for instance, w ith
frequent stops, congested traffic, and se tt roads (which cause constant
vibration), is n a tu ra lly sh o rter th a n it would be in a tow n w ith fight traffic
and sm ooth tarm a c roads. This increased cost, together w ith a higher
m aintenance cost, m ay be counteracted to some ex ten t by th e ” density-
of-traffic ” facto r shown in a n increase o f revenue for more passengers
carried per vehicle-mile. N evertheless we have in M anchester 170 buses
still running which h av e exceeded th eir eight years fife. These vehicles
are still being o p erated on th e peak-load services, as it would be obviously
WHALLEY : COMPARATIVE OPERATING COSTS OF
uneconomical to purchase brand-new vehicles for th e operation of the part day services, the loan charges per week on a double-deck bus being £8 (see table on Comparative Operating Costs).
(2 ) Op e r a t i o n a n d Ma i n t e n a n c e Co s t.
In considering operating costs th ere are certain factors which do not vary whatever m ethod of propulsion is used for th e vehicle. These are : the traffic charges (which include th e wages of drivers and guards, cash- clerks, and inspectors, ticket-printing, equipm ent on routes, uniforms, and cleaning of vehicles), general expenses (which include salaries and wages of officials, rents, rates, p rin tin g an d statio n ery , compensations—
accidents and em ployers’ liability—health, pensions, unem ploym ent, fires and other insurances, and telephones an d postages), licences (there is, of course, now no difference betw een th e licence p aid on th e petrol-engine vehicles and the heavy-oil-engine vehicles). All these item s per bus-mile only vary according to th e use m ade of th e vehicles, and in large towns, where there is a large peak load, it is extrem ely difficult to obtain a satis
factory mileage from all th e vehicles in th e fleet.
This leads to complications when a tte m p tin g to com pare th e costs to-day of a petrol-engine and an oil-engine vehicle. D uring th e last few years most municipalities have purchased oil-engine vehicles only, with the consequence th a t th e older petrol-engine vehicles hav e been relegated to the peak-load services. As a result th e average mileage of a petrol-engine bus is much lower th a n th a t of a corresponding oil-engine vehicle. In calculating the cost of a petrol-engine vehicle I have therefore had to assume th a t it is working under conditions id en tical w ith those of the oil
engine vehicle. Coming now to repairs an d m aintenance there is no appreciable difference in such item s as bodyw ork, painting, electrical repairs, m aintenance of tyres or fire appliances, a n d these item s have been treated as non-variable costs. W ith reg ard to th e tw o remaining items under this heading—chassis and engine— th ere is a difference. In the early days of the oil engine, overhauls were m uch m ore expensive than at present, owing to th e higher price of m aterials. C rankshafts, crankcases, etc., have to be considerably stronger in th e oil engine owing to the higher stresses with which they have to deal. T his difference in cost has now been considerably reduced, due to increased production, b u t nevertheless the opinion of the municipalities replying to th e Q uestionnaire is definitely that there is a higher cost in th e overhauling of th e oil engines. This varies from a few pounds to £20 per engine, w ith th e exception o f one undertaking, who state a cost of £46 more th a n a p etro l engine, although a t the same time two other undertakings claim th a t th e oil engine is cheaper to overhaul than the petrol ; b u t, taking th e average, th e cost of th e heavy overhaul of the oil engine is 0-08rI. per bus-mile m ore th a n t h a t of th e petrol engine.
I t is difficult to assess th e difference in d ay -to -d ay running maintenance, but the general opinion of th e different u n dertakings appears to be that, if anything, the advantage lies w ith th e oil engine, th e fuel-injection pump causing far less trouble th a n th e com bination o f m agneto and carburettor fitted to the petrol engine.
The following table shows th e com parative working expenses and final
PETROL AND COMPRESSION IGNITION ENG INED BU SES. 5 7 9
operating costs of two double-deck buses operating under norm al conditions and running an an n u al mileage of 45,000. The non-variable costs are abstracts from th e M anchester R evenue A ccount to d ate (5th F ebruary, 1939). The variable costs are average costs obtained from a sum m ary of the Questionnaire, and again M anchester figures are used for interest, loan charges, and additional provision.
Comparative Operating Costs o f T u o Double-deck B u se s (48-56 Seats) R u n n in g an A n n u a l M ileage o f 45,000.
T y p e of V ehicle : P e tro l
E n g in e . H eav y -O il E n g in e.
Cost of com plete vehicle . . . . £2,100 £2,200
Non-variable costs :
Traffic expenses . . . .
G eneral expenses . . . .
B uildings a n d fix tu re s
M achinery a n d to o ls . . . . S u p e ra n n u atio n f u n d . . . . L ab o u r co sts of fu elin g a n d lu b r ic a tin g . R epairs a n d m a in te n a n c e :
B odyw ork a n d p a in tin g
E lectrical . . . .
T yres a n d fire ap p lian ces
P en ce p er Bus-M ile.
5-462 0-939 0-104 0-088 0-343 0-066
| 0-816
E xcise licence . . . . .
P.S.V . licence . . . . .
7-818 £1,466
86 2
£1,466 86 2
Variable costs :
R epairs a n d m a in te n a n c e :
Chassis a n d engine . . . .
99 99 . . . .
F uel (co n su m p tio n only) 9 9 . 9» 9 9
L u b ric atin g oil (co n su m p tio n only)
»» 99 99 99
1-333 1-413 2-800 1-443 0-057 0-081
£1,554
250 525 11
£1,554
265 271 15 Comparative w orking expenses :
In te re s t on lo an . . . . . R ed em p tio n of d e b t . . . . A dditional p ro v isio n fo r ren ew als
£2,340 73 236 87
£2,105 77 247 91
Comparative operating costs £2,736 £2,520
Difference in fa v o u r o f heavy-oil buses .
( £2
i = 1-152 ( bus-
16 d. p er mile.
Repairs and m aintenance cover all th e costs of both th e day-to-day m aintenance in th e garages, regular dock overhauls, and com plete over
hauls. F rom th e retu rn s m ade by th e different undertakings it appears
th a t everybody has now ad o p ted a more or less sim ilar system . Engine
and chassis are light docked every 20,000 miles, and this dock generally
5 8 0 WHALLEY : COMPARATIVE OPERATING COSTS OF
consists of the removal of th e cylinder head, a tte n tio n to valves, de
carbonizing, dropping of the sump, and inspection of th e bearings, cleaning of oil filters and oil system generally, refilling w ith fresh oil, and the checking of the fuel-pump tim ing. W ith some undertakings th e fuel-pump calibration is also checked a t th e same tim e.
Up to a few years ago it was th e custom to p u t all vehicles through a complete overhaul after 60,000 miles, b u t owing to th e improvements in material and design, this figure has g radually been increased, until now 100,000 is looked upon as being an ap p ro p riate mileage a t which to carry o u t' a complete overhaul. U nfo rtu n ately on fa st City services, where engines are subject to very severe tre a tm e n t, it is n o t generally advisable to let the engine ru n for such a period, and in m an y undertakings it is customary therefore to carry out a sem i-overhaul a t 50,000-60,000 miles or to change the engine u n it for a thoroughly overhauled unit.
At the complete overhaul of the engine it is usually necessary to either re-grind the sleeves or cylinder bore and fit oversize pistons, or, alterna
tively, re-sleeve back to stan d ard size. T he crankshaft will require re-grinding, and all th e bearings, b o th m ain and big-end, will require re
newal. I t wall also be found th a t certain of th e valve-seats will require new' inserts. In the larger undertakings th e engine, afte r such an overhaul, is thoroughly bench-tested and ready to s ta r t a fresh life, as good as new.
The costs given for this overhaul v ary from £30 to £90, b u t in comparing the costs of the overhaul of th e petrol and oil engine, I have used the Manchester figures, which are com parable w ith sim ilar undertakings, and the cost of overhaid of th e oil engine is ap proxim ately £20 more th an the petrol engine. Certain engine-m anufacturers u n d ertak e th e overhaul of their engines for users, and we in M anchester have had oil engines over
hauled by w'ell-known m akers a t a cost of £75 n e tt. Our own price for this job over twelve m onths has worked o u t a t £74 8s., so th a t I th in k we may say th a t the figures I have used are fair and reasonable. Some under
takings claim, in their replies to the Q uestionnaire, to have carried out their overhauls for considerably less th a n this, b u t you will appreciate that circumstances alter cases, and there m ay be p articu lar reasons which result in the engine not needing such heavy repairs as are required after 60,000 miles’ arduous service in heavy city traffic.
The distinguishing u n it between th e oil engine an d th e petrol engine is the fuel-injection pum p which takes th e place of both carburettor and magneto on the petrol engine. This pum p is rem arkably efficient, and in fact it is largely due to this pum p efficiency th a t th e high-speed com- pression-ignition engine has m ade such progress. In th e m aintenance of the pump we find it advisable to check th e calibration a t every light dock (20,000 miles), b u t the actual repair an d replacem ent required by the pump even a t 100,000 miles—are very sm all. M ost of th e large under
takings now have an electrically driven m achine for testin g and calibrating
ue -injection pumps, and these have proved o f g reat service, inasmuch as
t le uel consumption has been im proved as a resu lt o f a periodic calibration
on th e machine. The following table shows th e pum p-settings which have
een standardized in M anchester, and th e effect of using an d maintaining
these settings has been an im provem ent in th e fuel consum ption of the fleet
of half a mile per gallon :__
PETROL AND COMPRESSION IGNITION ENG IN EI) BUSES. 5 8 1
C ali
b ra tio n L e tte r.
Code.
O verload S e ttin g ,
C.C.
F u ll-lo a d S e ttin g ,
C.C.
G o v ern o r G o v ern o r R .P .M . M ax.
Springs. M in. M ax. M .P .H .
A A.2M 7E
B.2M 7E 9-4 9-4
7-7 7-0
7023/84 7023/78
180 770 30-4
B A.2M 6E
B.2M 6E
9-4 7-0 7023/36
7023/75 7023/38
180 870 30-4
C C.3M7E 9-4 8-4 7023/84
7023/78
180 770 30-4
D C.3M6E 9-4 7-7 7023/36
7023/75 7023/38
180 870 30-4
G A .2S7K
B .2S 7K
9-4 7-7 7023/84
7023/78 7023/38
180 770 32-2
H A .3S7H
B .3S7H
9-4 7-9 7023/84
7023/78
180 770 30-7
L — 4L4E 9-3 8-6 7023,84
7023/78
180 800 33-5
M — 4L6E 9-3 7-6 7023/84
7023/78 7023/38
180 900 31-5
N — 4T5F 9-3 8-2 7023/84
7023/78
180 800 32-9
Ke y. F irs t (letter).
A B C D T h ird (letter).
M S L T
H e ad s.
A ty p e B „ C „ D „
Chassis.
T y p e x D .D . T y p e x S.D . T y p e z D .D . T y p e z S.D .
F if th (le tter).
E F H K
S econd (N um ber).
2 3 4
E ngine.
4-7/16 X 6 4-7/16 X 5 J 4£ X 5 i
F o u r th (N um ber). D ifferential ra tio . 5-4 5-5 6-5 5-75 T y re Size.
9 - 0 0 X 2 0 2 3 0 X 2 0 8 - 2 5 X 2 2 8 - 2 5 x 2 4
I cannot too strongly urge engineers to p a y m ost careful atte n tio n to th e settings and calib ratio n of th e fuel-pum ps.
Fu e l s.
The ty p e o f fuel used has obviously a very im p o rtan t bearing on th e question of operating costs. Some years ago in M anchester we were p u t to a g reat deal of unnecessary expense through using an unsuitable petrol, and we have since ta k e n p articu lar care to have sam ples regularly tested.
The petro l which gave trouble h ad a final boiling po in t of 2393 C., w ith a result th a t crankcase dilution was excessive and engine trouble followed.
As a result of our experience we consider th a t a p etrol w ith a final boiling
5 8 2 WHALLEY : COMPARATIVE OPERATING COSTS OF
point of over 200° C. is unsuitable for our purpose. T he following is an average test of a petrol which has been found suitable :—
Specific g ra v ity D istillation test :
F irs t drop collected a t . B etw een first d ro p a n d 105° C
105° C. a n d 150° C.
150° C. a n d 180° C.
Above 180° C.
Loss on distillatio n
0-741
41-0° C.
37-5%
38-0%
16-5%
6-5%
1-5%
100% M axim um te m p e ra tu re of d istilla tio n — 199-5° C.
Sulphuric-acid test— A cid lay e r assum es lig h t o range-yellow coloration.
Effect on b rig h t copper— Nil.
D octor test— N egative.
Colour— W ater-w h ite.
This test can be carried o u t by th e chem ical la b o rato ry of th e Corpora
tion, and in fact frequent test-sam ples are ta k e n an d tested during the period of a contract. The octane num ber of th e sp irit is given by th e suppliers as 69-5.
The oil used for our com pression-ignition engines, which the general public will insist on calling “ crude ” oil, is, as you are well aware, a high- grade gas oil. I t is much more difficult for th e users to m ake certain that the fuel is up to specification, th e engine te s t being, I th in k , th e only real criterion. From th e replies to th e Q uestionnaire, th e m ajo rity of under
takings are using well-known sta n d ard gas oils, o f which th e following is a typical specification :—
Specific g ra v ity a t 60° F . F lash-point (P.M.)
Viscosity (Redw ood) a t 70° F .
„ 100° F . Calorific value
Spontaneous ig nition te m p e ra tu re Carbon residue
Ash . Sulphur
C etane n u m b er . In itia l boiling p o in t
10% over a t 20
%
30%40%
50%
60%
70%
80%
90%
05%
F in al boiling p o in t R ecovery Residue Loss . P our-p o in t .
0-845 220° F .
42 seconds.
36 „
19,500 m in im u m B.T.IT.
240° C.
0-0 1% 0-003%
0-13%
57-5 m inim um . 240° C.
263 272 278 285 291 298 306 318 340 362 B elow 370° C.
97%
1-5%
1-5%
10° F .
S n W. ? Si SpeCr iiCil t i o n i s ’ i n m y o p i n i o n ,
b e tte r
t h a nth e B ritish Standard
P c a t i o n
for
h i g h - s p e e d d i e s e lfuel No.
2 0 9 ,published J u ly 1937, the
la tte r perm itting a m axim um viscosity o f 45 secs. (Redwood) a t 100° F . Our experience in M anchester leads us to th in k th a t th e viscosity we are now using—ab o u t 36 secs. (Redwood)—is m uch more suitable, as th ere are difficulties in supplying a higher viscosity fuel to th e engine.
I have m ade some experim ents w ith a view to com paring different gas oils as regards s ta rta b ility in our engines. A n auxiliary ta n k filled w ith a m ixture of ice and salt w as connected in series w ith th e engine-cooling system, and an independently driven circulating pum p used to circulate the brine m ixture through th e engine u n til th e tem p era tu re of th e cooling w ater
was brought dow n to 15° F .
These tests showed th e necessity of using lubricating oil w ith a good cold test, as it was necessary to tu rn th e engine a t 80 r.p.m . to be certain of a start, under these conditions of extrem e cold.
Comparative fuel tests are also m ade w ith engines on th e test-bench a t the Works, w here we have tw o H eenan an d Froude electro-dynam ic engine-testers, th e following being th e resu lt of a typical te s t :—
F u e l “ A ” -—A verage of 5 ru n s of 15 m ins. each :—- 1400 r.p .m ., 76-64 b .h .p ., 0-603 p t. p er b .h .p . F u e l “ B ” •—A v erag e of 5 ru n s of 15 m in s. each :—
1400 r.p .m ., 78-75 b .h .p ., 0-.581 p t . p e r b .h .p .
These tests are o f value as a com parative te s t only, due to th e fact th a t our flowmeters are calibrated for p etro l an d this te s t was ta k e n on an oil engine. The perform ance o f th e engine was b e tte r in every w ay when running on fuel “ B .”
W hatever m ethod o f grading or ra tin g th e fuels is ultim ately decided on, one of th e m ost im p o rta n t points to th e user is t h a t th e ignition delay angle should be as sm all as possible, a n d it has been found th a t th ere is a direct relationship betw een th e anti-knock value an d th e delay angle, zero knock or the best possible sm ooth running being equal to 3-5° o f ignition delay.
Good ignition qualities, low viscosity, freedom from im purities, and absence of w ax separation are all desirable in a fuel oil for compression- ignition engines. E ase o f sta rtin g on b o th oil and petrol engines has a direct bearing on cost, for unless th e engine will s ta rt easily after standing all night, it is necessary to have either special gangs of m en going round starting up, or self-contained p ortable petrol-engine-driven starters, or even, in m an y instances, i t becomes necessary to tow th e vehicle w ith another one, adding considerably to th e running costs.
A direct-injection oil engine norm ally has a b e tte r s ta rt th a n a sim ilar petrol engine, b u t w ith some o f th e indirect ty p e th e re are sta rtin g diffi
culties, p artic u larly in cold w eather. W e have found th a t by using double pole-heater plugs connected d irect to th e 12-volt lighting and startin g battery, it is n early alw ays possible to g et a cold sta rt. The heater-plug is controlled by a special sw itch, which, w hen tu rn ed in to th e first position, heats th e plugs, including a tell-tale plug in th e d riv er’s cab. W hen th is is glowing brightly, th e sw itch is m oved in to th e second position which operates th e starter-m o to r. W e have also developed in some o f our garages a system o f ra d ia to r heating, w hereby low-pressure steam is allowed to bubble th ro u g h th e rad ia to r th ro u g h o u t th e night, th e steam - pipe being connected to a special ta p a t th e b ottom of th e rad iato r-tan k .
PETROL AND COMPRESSION IGNITION ENGINED BTJSES. 5 8 3
5 8 4 WHALLEY : COMPARATIVE OPERATING COSTS OF
This has proved very satisfactory and econom ical for both petrol and oil engines, as the tem perature of the engine is m ain ta in ed a t over 100° F.
throughout the night.
In Manchester it is our practice to centrifuge all fuel oil before delivery to the buses, oil being received from th e co n tracto r into th e large storage- tank, from which it is pum ped through a centrifuge into th e service-tank.
Although there are only two other undertakings who have reported th at they also use the centrifuge, we have form ed a definite opinion th a t this process is a profitable one. The actu a l cost of centrifuging, including all capital charges of th e p lan t and labour, is less th a n O ld . per gallon, and it has been noticeable when one of th e centrifuges has been tem porarily out of service, complaints from th e buses belonging to th a t garage regarding black smoke, etc., have im m ediately increased. The m ajority of the undertakings have reported th a t th ey now g et very few com plaints from the police or public regarding fumes, th is being due to th e b etter attention to the pum p and atom izer system s. Seventeen of th e undertakings replying have installed power-driven testin g m achines for calibrating the fuel-pumps, and report savings of from 5 to 10 per cent. I n Manchester it is now our practice to check every pum p a t 20,000 miles, and this has resulted in an im provem ent of 5 per cent, in th e fuel consum ption of the fleet.
Lu b r ic a t io n.
The question of lubrication is one on which, as you know, m any papers have been w ritten, and m any more will be w ritten. Most engineers hold very decided opinions, some believing in th e cheapest oils, and others in the very highest quality. From th e retu rn s m ade by th e undertakings it appears th a t m ost m unicipal operators ta k e th e m iddle course, using a lubricant of a reasonable price and m aking no a tte m p t to reach phenomenal oil-consumption figures in miles per gallon. Tests have been carried out with all types of oil, and in our opinion th e b e tte r consum ption obtained from the higher-quality oils was n o t sufficient to offset th e increased cost.
Provided an oil of good cold te st and as low a viscosity as can be used with safety is specified, no harm will result, and th e w ear figures will not be excessive. In fact in M anchester w ith a m edium -priced oil and the follow
ing specification :—
Specification No. 1. (Diesel lub. oil.) Specific g ra v ity a t 60° F .
Closed flash . . . .
Open flash . . . .
V iscosity (Redw ood) a t 70° F . .
„ 140° F . . . » . . „ „ 200° F . . V iscosity index
Cold te s t p o u r I.P .T . D em ulsibility n u m b er I.P .T . F a tty oil, % .
Carbon residue R a m s b o tto m A
” >> >, B
Colour . . . .
cylinder-wear figures as low as 12,000 miles per 0-001 inch for petrol engines, 15,000 miles per 0-001 inch for direct-injection oil engines and
W in te r. Sum m er.
0-905 0-907
440° F . 440° F.
460° F . 460° F.
1120 secs. 1450 secs.
136 „ 165 „
56 „ 62 „
85 85
5° F . 5° F.
3 4
N il Nil
0 1 9 % 0-25%
1-12% 1-22%
D eep p a le V ery light red
PETROL AND COMPRESSION IGNITION ENGINED BUSES. 5 8 5
33,000 miles per 0 001 inch for indirect-injection oil engines are regularly obtained. These figures are n o t isolated cases, b u t are averages of a large number of engines.
Twenty-two undertakings have given details o f th e specification of the lubricating oils which th e y use. I t is n o t necessary to give all these in detail, as fifteen of th em are sim ilar to th a t already given for M anchester.
Three undertakings are using oil sim ilar to Specification Xo. 2 (below), the price of this being ap proxim ately 60 per cent, more per gallon th a n the oil in the M anchester Specification.
Three undertakings are each using special oils. Specification Xo. 3 (a) is apparently a solvent-refined oil of a low viscosity w ith a very high viscosity index (108), a n d th e price is slightly higher th a n th a t of the previously m entioned solvent oils. A specially tre a te d oil w ith a graphite content is shown in Specification Xo. 3 (b) and th is has th e highest viscosity index of any oil reported— viz., 111. The th ird undertaking which is using special oil rep o rts th a t it is using lubricating oil which has been electrically tre a te d , b u t it does n o t pass an y com m ent on th e results obtained.
Specification N o . 2.
Specific g ra v ity a t 60° F . Closed flash .
Viscosity (R edw ood) a t 70° F .
„ 140= F .
„ 2 0 0° F . Cold te s t p o u r I .P .T .
D em ulsibU ity n u m b e r I .P .T . C arbon residue R a m s b o tto m A
»> »» »» B
0-880-0-885 440-450= F . 2200-2300 secs.
255-260 „
80-83 15° F . 0-30-0-35%
0-80-0-90%
Specification N o . 3.
Specific g ra v ity a t 60° F . Closed flash .
Open flash
V iscosity (R edw ood) a t 70° F .
„ 140= F.
„ „ „ 200° F .
V iscosity in d ex Cold te s t p o u r I.P .T . D em ulsibihty n u m b e r I .P .T . F a tty oil, % .
C arbon resid u e R a m s b o tto m A
>» >> ,, B
(a). (b).
0-873 0-882
405° F . 430° F .
415° F. 450° F .
660 secs. 1450 secs.
107 „ 185 „
53 „ 71 „
108 111
15° F . 0° F .
1 4 |
Nil H %
0-42% 0-52%
— 1-35%
Finally there is one o th e r interesting point, and th a t is th a t one m unici
pality with a fleet of over 100 buses has entered into a mileage contract for the lubrication of th e ir vehicles, th e con tracto r ap p aren tly being responsible for all th e lubrication o f th e fleet and being paid so much per bus-mile.
Ta x a t io n.
The question of ta x a tio n has a g reat bearing on th e developm ent of any
new type of prim e m over for ro a d -tran sp o rt work. The absence of
additional ta x a tio n u n d o u b ted ly assisted th e early developm ent of th e oil
engine, th e position in 1932 being th a t whereas petrol was carrying a ta x of
8d. per gallon, gas oil was free of tax , and th e licence for th e oil-driven
5 8 6 WHALLEY : COMPARATIVE OPERATING COSTS OF
vehicle was exactly th e same as th e p etro l vehicle. In 1933, however, there was an additional ta x of Id. per gallon on b o th gas oil and lubricating oil and the licence of a double-deck fifty-tw o-seater bus was increased from
£86 8s to £148 if driven by an oil engine. I n 1935 th e additional R oad Fund tax was removed, and th e 8d. per gallon fuel ta x p u t on gas oil in the same way as on petrol. Finally, in 1938 th ere was a n additional Id. per gallon, making 9d. on both petrol and fuel oil. This is shown clearly in the following table :—
52 -Seaters.
P e tro l.
1932.
H e a v y Oil.
T ax . •
L u b ricatin g oil . Licence
8 d.
£86 8s.
1933-34.
T a x .
L u b ric a tin g oil . L icence
. Nil
! £86 8s.
T ax .
L u b ricatin g oil . Licence
8 d.
Id.
£86 8s.
1935-36.
T a x .
L u b ric a tin g oil . L icence
. I d . . I d . . £148
T ax . . . .
L u b ricatin g oil . Licence
8d.
Id.
£86 8s.
1938-39.
T a x .
L u b ric a tin g oil . L icence
. 8 d . . I d . . £ 8 6 8 s .
T ax . . . .
L u b ricatin g oil . Licence
9d.
Id.
£86 8s.
T a x .
L u b ric a tin g oil . L icence
. 9 d . . I d . . £ 8 6 8 s.
I t is interesting to note th a t th e a m o u n t p aid for m otor-om nibus licences in Manchester for the financial year (1937-38) was as follows :—
R o a d F u n d licences
Traffic C om m issioner’s licences
£45,955 2,555
£48,510
The am ount paid in ta x on p etrol a n d h eav y oil for th e financial year (1937-38) was £104,716. The am ount p aid in ta x on lubricating oil was £385. Thus th e to ta l ta x a tio n p aid was £153,611.
The table in Appendix V illu strates th e effect of th e varying taxation on the running costs and savings in favour of th e oil engine.
The average fuel cost per mile of th e u n dertakings replying to the Questionnaire were as follows :—
Average Cost p e r M ile .
D o u b le D ecks. Single Decks.
P e tro l . . . .
H eav y oil, d irect . . . .
„ in d irect . . . .
2-889 1-423
2-889 1-569
2-441 1-220
2-441 1-367 Saving in fav o u r of oil engine (in pence
per bus-mile) . . . 1-466 1-320 1-221 1-074
PETROL AND COMPRESSION IGNITION ENGENED BU SES. 5 8 7
To conclude, it null be no ted from th e sum m ary of th e Questionnaire th a t there are now very few com plaints against th e oil engine. I t has the advantage th a t th e brake th erm al efficiency is approxim ately 32 per cent., as against 22 per cent, for th e p etro l engine and, fu rth er, it runs m ost economically a t ab o u t 60 per cent, of full load, which is th e condition under which the engine is m ostly running in service. The perform ance on the road is generally ad m itted to be a gear b e tte r th a n a petrol-driven bus, and experiments are now being m ade w ith over-speed gear-boxes so as to give a higher road speed and ta k e a d v an tag e of th e good torque w ith th e diesel engine a t low speeds. F u rth e r, th e re is less risk of fire, and no restriction on the storage and handling o f th e fuel.
The oil engine to -d ay runs com paratively quietly, a n d in fa c t m any passengers cannot te ll th e difference. There rem ains, then, th e saving in fuel, which averages l-357d. per mile for a double-deck bus (see p. 579), from which m ust be deducted th e slight e x tra m aintenance cost of O-OSOri.
per mile, the higher lubrication cost o f 0-024d. per mile and th e additional debt redem ption charges of OlOlrf. per mile, leaving a n e tt saving per bus- mile of lT 52d., equivalent to £216 per vehicle per annum on a basis of an annual mileage of 45,000.
As to the future, we look forw ard to a reduction in th e power-weight ratio of the com pression-ignition engine a n d a fu rth e r reduction in th e first cost. There is also a possibility of fu rth e r economies w ith th e introduction of super-charging an d th e tw o-stroke engine.
Experiments are actively in progress w ith th e E rre n system of injecting a percentage of hydrogen gas into th e com pression-ignition engine, which it is claimed can produce a fu rth e r econom y of 30 per cent, provided hydrogen can be purchased a t a reasonable price. I t is sta te d th a t if hydrogen could be purchased a t 8d. per 1000 cu. ft., it would be equivalent to diesel oil a t 3d. per gallon or p etrol a t 2d. per gallon. The E rre n system is claimed to give smoother running an d a clean exhaust, in ad d itio n to fuel economy.
There are also th e com pressed-gas and self-contained producer-gas vehicles to be considered as rivals to th e diesel engine. In certain countries on the C ontinent it has been m ade com pulsory for th e owners to operate a minimum of 10 p er cent, o f th e ir fleet on hom e-produced fuels, and th is has led to a large num ber o f these gas-producer vehicles being p u t into service.
E x p e r i m e n t s a r e a g a i n s t a r t i n g i n t h i s c o u n t r y , a n d i t w i l l b e i n t e r e s t i n g t o s e e w h e t h e r t h e s y s t e m c a n b e s u c c e s s f u l l y a p p l i e d t o p a s s e n g e r - t r a n s p o r t w o r k .
Transport engineers are alw ays
w i l l i n gto experim ent w ith new fuels provided th a t there is some reasonable chance of th eir being a success, and provided a suitable fuel, available in sufficient quantities, is produced, engine-builders are q uite p rep ared to a lte r or re-design th e ir engines to suit. The qualities we desire in a fuel are t h a t it should be easily obtained, safe to store an d handle, a n d stable u n d er norm al storage conditions.
I t should give easy sta rtin g , sm ooth running, an d clean com bustion, leave
no undesirable residue in th e cylinders, be stab le in price, and cheap. I t is
the a u th o r’s contention t h a t a t th e m om ent th e com pression-ignition
engine using sta n d a rd gas oils stan d s unchallenged as th e cheapest, safest,
and best m ethod of propelling a road passenger-transport vehicle.
NUMBEROFBUSESREQUIREDFOR SERVICE
A P P E N D IX I.
B uses Required fo r Service.
WHALLEY : COMPARATIVE OPERATING COSTS OF
PM' PER IO D
uu
\ i
A P P E N D I X I I .
P articulars o f Passenger Vehicles Operated by M em bers o f the M .T . an d T .A .
A t :
3 1st D ecem ber,
1934.
3 0 th J u n e ,
1935.
31st D ecem ber,
1935.
3 0 th J u n e ,
1936.
31st D ecem ber,
1936.
30 th J u n e ,
1937.
31st D ecem ber,
1937.
30 th Ju n e ,
1938.
M o to r o m n ib u ses : P e tro l :
S ingle-deck . . . 2343 2206 2063 1960 1805 1688 1583 1433
D o u b le-d eck . . . 2013 2512 2490 2447 2361 2174 2026 1904
T o ta l . . . . 4956 4718 4553 4407 4166 3862 3609 3337
Oil :
Single-deck . . . 225 328 450 521 605 699 853 935
D o u b le-d eck . . . 919 1379 1813 2065 2708 3252 4034 4486
T o ta l . . . 1144 1707 2263 2586 3313 3951 4887 5421
T o ta l m o to r-b u ses :
S ingle-deck . . . 2568 2534 2513 2481 2410 2387 2436 2368
D o u b le-d eck . . . 3532 3891 4303 4512 5069 5426 6060 6390
T o ta l . . . 6100 6425 6816 6993 7479 7813 8490 8758
TETROLANDCOMPRESSIONIGNITIONENGINEDBUSES. 589
Ill
O l
COo
A P P E N D I X I I I .
M echanically Propelled R oad Vehicles— Great B rita in .
V ehicles fo r w hich licences w ere c u rre n t d u rin g q u a r te r e n d ed 3 0 th S ep tem b er, 1935, 1936, 1937 a n d 1938.
C om piled fro m M in istry of T ra n s p o rt R e tu rn s . A .— Ha c k n e y Ve h i c l e s.
- N u m b e r of V ehicles. P e r c e n t, of T o ta l. In c re a se o r D e crease
in T h ree Y e ars.
1935. 1936. 1937. 1938. 1935. 1936. 1937. 1938. N u m b e r. P e r c en t.
In te m a l-e o m b u s tio n en g in es : L ig h t o i l :
(а) U p to e ig h t s e a ts . (б) O v e r e ig h t s e a ts . H e a v y oil, e tc .
E le c tric a lly -p ro p e lle d (tro lle y
vehicles) . . . .
T ra m c a rs . . . .
38,331 40,499 5,541 1,176 10,872
36,893 38,981 8,547*
1,588 10,260
34,784 35,860 12,997 2,125 9,657
34,723 32,960 17,322 2,725 8,988
39-75 42-00 5-75 1-22 11-28
38-32 40-49 8-88 1-65 10-66
36-45 37-58 13-62
2-23 10-12
35-90 34-08 17-91 2-82 9-29
- 3,608 - 7,539 + 11,781 + 1,549 - 1,884
- 9-412 - 18-61 + 212-62 + 131-72 - 17-33
T o ta l 96,419 96,269 95,423 96,718 100-00 100-00 100-00 100-00 + 299 + 0-31
O►t)
i-3cn
* In c lu d e s 1 p e tro l a n d coal-gas fuel vehicle.
.
B . — Go o d s Ve h i c l e s.
(E x clu d in g a g ric u ltu ra l v a n s, e tc ., sh o w m en ’s special vehicles.)
N u m b e r of V ehicles. P e r c e n t, of T o ta l. In c ro a se o r D ecrease in T h re e Y ears.
1935. 1936. 1937. 1938. 1935. 1936. 1937. 1938. N u m b e r. P e r c e n t.
In te m a l-c o m b u s tio n en gines : L ig h t o i l :
(a) U p t o 2£ to n s 360,309 382,777 401,450 415,842 85-31 85-93 86-47 86-80 + 55,533 + 15-41
(6) O v er 21 to n s 52,644 52,251 50,988 49,299 12-46 11-73 10-96 10-30 - 3,345 - 6-35
H e a v y oil, e tc . 5,417 6,149* 7 ,1 0 7 1 8,552 1-28 1-38 1-6 1-78 + 3,135 + 57-87
C oal gas . . . . 14 7 12 18 — — — — + 4 + 28-57
S te a m -d riv e n 2,018 1,671 1.283 986 0-5 0-38 0-26 0-20 - 1.032 - 51-14
E le c tric a lly p ro p elled 1,885 2,600 3,320 4,397 0-45 0-58 0-71 0-92 + 2,512 + 133-26
T o ta l 422,287 445,455 464,160 479,094 100-00 100-00 100-00 100-00 + 56,807 + 13-45
* In c lu d e s 5 p e tro l a n d coal-gas vehicles, f In c lu d e s 7 p e tro l a n d coal-gas vehicles.
o<
CD
PETROLANDCOMPRESSIONIGNITIONENGINEDBUSES.
592 WHALLEY : COMPARATIVE OPERATING COSTS OF
A P P E N D I X IV .
Schedule showing the A n n u a l S u m R equired to he S e t A sid e a nd to Accumulate at 3 per cent. Compound Interest, in Order to R ep a y a L o a n o f £2200 in Eight Years.
Y ear.
1.
A n n u a l P a y m en t in to th e F u n d .
2.
A n n u a l I n te r e s t on A ccu m u latio n s.
3.
T o ta l, C olum ns 2 a n d 3.
4.
T o ta l in Fund a t E n d of E a c h Year.
5.
£ s. d. £ s. d. £ s. d. £ s. d.
1 247 8 1 — 247 8 1 247 8 1
2 247 8 1 7 8 5 254 16 6 502 4 7
3 247 8 1 15 1 4 262 9 5 764 14 0
4 247 8 1 22 18 0 270 6 11 1035 0 11
5 247 8 1 31 1 0 278 9 1 1313 10 0
6 247 8 1 39 8 1 286 16 2 1600 6 2
7 247 8 1 48 0 2 295 8 3 1895 14 5
8 247 8 1 56 17 6 304 5 7 2200 0 0
Statement showing the A d d itio n a l P rovision required E ach Y ea r to Reduce the P eriod to 6$ Y ears.
Y ear. A m o u n t a s p er Col. 4 A bove.
A d d itio n a l
P ro v isio n . T o ta l.
£ s. d. £ s. d. £ s. d.
1 247 8 1 91 1 2 338 9 3
2 254 16 6 83 12 9 338 9 3
3 262 9 5 75 19 10 338 9 3
4 270 6 11 68 2 4 338 9 3
5 278 9 1 60 0 2 338 9 3
6 286 16 2 51 13 1 338 9 3
m 147 14 1 21 10 5 169 4 6
147 14 2
U 304 5 7
£2200 0 0 £451 19 8 £2200 0 0
I t will be seen t h a t should th e vehicle la s t th e full p e rio d of eig h t years, there is
£451 19s. plus in terest a ccru ed in th e R en ew als F u n d av ailab le for o th er purposes.
A P P E N D I X V.
Schedule show ing the E ffect on P ow er a n d L u bricating Costs o f T a x a tio n on a S ta n d a rd D .D . B u s (4 8 -5 6 Seats) R u n n in g a n A n n u a l M ileage o f 45,000.
Co s t p e r Bu s- Mi l e. (Market fluctuations ignored.)
1932. 1934. 1930. 1938.
P e tr o l E n g in e . H .-O il E n g in e . P e tr o l E n g in e . H .-O il E n g in e . P e tr o l E n g in e . H .-O ll E n g in e . P e tr o l E n g in e . H .-O ll E n g in e .
L ic e n c e a m o u n t P e tr o l o r fu el o il p e r
g a ll. .
P e tr o l o r fu el o il ta x p e r g a ll.
E n g in e lu b r ic a tin g oil p e r g a ll.
E n g in e lu b r ic a tin g oil t a x p e r g all.
C o m p a r a tiv e c o s ts . D iffe re n c e In fa v o u r
of C .I. e n g in e
£ 8 0 8s.
4-10d.
8 0 0 13-20
P en co p .b .m . 0-401 0-885 1-702 0-053
£8 0 8s.
3-025(1.
15-200 P en c o p .b .m . 0-401 0-414
0-070
£8 0 8s.
4-10(1.
8-00 13-20 1-00
P e n c e p .b .m . 0-401 0-885 1-702 0-053 0-004
£148 3-025(1.
1-000 15-200 1-000
P e n c e p .b .m . 0-789 0-414 0-114 0-070 0-005
£ 8 0 8s.
4-lfld.
8-00 13-20 1-00
P onco p .b .m . 0-401 0-885 . 1-702 0-053 0-004
£ 8 0 8s.
3-025d.
8-000 15-200 1-000
P e n c e p .b .m . 0-401 0-414 0-914 0-070 0-005
£8 0 8s.
4-10d.
9-00 13-20 1-00
P en c o p .b .m . 0-401 0-885 1-915 0 0 5 3 0-004
£8 0 8s.
3-025d.
9-000 15-200 1-000
P e n c e p .b .m . 0-401 0-414 1-020 0-070 0-005
3-101 0-951 3-105 1-398 3-105 1-870 3-318 1-985
2-150 1-707 1-235 1-333
PETROLANDCOMPRESSION IGNITION ENGINED BUSES. 593
Olco
A P P E N D I X V (continued).
Ne t t Po w e r a n d Lu b r i c a t i o n Co s t s a n d Ta x a t i o n. ( C a lc u la te d t o t h e n e a r e s t £ .)
N e tt. T a x . N e tt . T a x . N e tt. T a x . N e tt. T a x . N e tt. T a x . N e tt . T a x . N e tt . T a x . N e tt . T a x . L ic e n c e .
P e tr o l o r fu e l oil E n g in e lu b r ic a tin g oil
£1 6 6
£1 0
£86
£319 £78
£14
£ 8 6
£166
£10
£86
£3 1 9
£1
£78
£14
£148
£21
£1
£1 6 6
£ 1 0
£86
£319
£1
£ 7 8
£14
£86
£171
£1
£1 6 6
£ 1 0
£86
£359
£1
£78
£14
£86
£193
£1
T o ta ls £176 £405 £92 £86 £176 £406 £92 £1 7 0 £176 £4 0 6 £ 92 £ 2 5 8 £176 £446 £ 92 £2 8 0
A g g re g a te c o s ts £581 £178 £582 £262 £582 £350 £ 6 2 2 £372
D iffe re n c e in f a v o u r
o f C .I. e n g in e £4 0 3 £ 3 2 0 £2 3 2 £2 5 0
,EY: COMPARATIVEOPERATINGCOSTSOF
A P P E N D IX Va. 1 9 3 2
£.581
£l78
POWE
1934
ÎS 82
262
R AND LUB^
OIL T A X
1 9 3 6
¿582
PETROL & LUB*
OIL (NETT) '
1938 [622
¿ 3 7 2
FUEL OIL & LUB?
OIL (NETT) LICENCE CHARGE
Ot
C DOl
PETROLANDCOMPRESSIONIGNITIONENGINEDBUSES.
