- Reprinted from
February 18, 1956
- “The Times”
of the Transport World
- 3-16 Woburn Place,
COMMERCIAL VEHICLE TEST
Bold Design of the Birch Taxicab
IMPROVED APPEARANCE, COMFORT AND ECONOMY
It requires a great deal of courage to attempt to break
away from tradition and when it is a tradition supposedly dear to the hearts of
Londoners, the risk of incurring wrath or ribaldry is great. The basic layout of
the London-type taxicab has remained unchanged for so many years that it has
become traditional; it has taken the courage and imagination of Mr. John Birch,
of Birch Bros., Limited, bus, coach and taxicab operator, to attempt the design
of a new London
- proved. It is the intention of the
Birch company to put the prototype in service with its own fleet for a period of
six months or so, during which time decisions regarding production, selling
price and any necessary modification of design will be taken.
Birch taxi has been designed from the premise that the traditional layout is
wrong because the main passenger seat is in the most
pleasing general lines and the interior arrangement of the Birch taxi are well
illustrated in these two pictures.
- taxicab that would be more in keeping with the high standards of
comfort and appearance attained by other forms of road transport vehicles, while
yet conforming with the precise constructional regulations laid down by the
Commissioner of Metropolitan Police. That
the new design meets the police requirements was proved by the issue towards the
end of December of a licence to operate the prototype vehicle; that performance
and fuel economy are good, even highly favourable, was indicated by our recent
two-day road test of the same vehicle; that passenger comfort and convenience
are of a high order was testified to by a number of critical passengers carried
during the test; whether Londoners (taxicab operators, drivers and passengers)
will take to the new vehicle has yet to be
- uncomfortable position -
over the back axle - and that luggage is carried where it is open to the
elements, where it cannot be properly safeguarded and where it can overhang the
near side of the vehicle. The new design removes these disadvantages by adopting
a body style rather similar to a modem estate or dual-purpose car. The main
passenger seat is placed well forward of the rear axle at about the midships
position in the body, with the usual access doors on each side.
service records show that in only about one hiring in ten are more than two
passengers carried the principal seat provides exceptional comfort for two with
a high squab brought up to form a headrest.
When more than two passengers are carried this seat, no longer restricted
in width by the wheel arches, will seat three abreast and a
- seat for a fourth
passenger is fitted facing rearward in what was formerly the luggage space
alongside the driver. The space behind the main seat provides more than twice
the usual luggage space, to which wide access is arranged through a rear-hung
door on the near side. An
automatically retracting sprag, by which the door can be propped open, is
driver's compartment, which includes a space for the taximeter on the near side,
is separated from the rest of the body by a half-glazed partition.
A sliding full-drop window, operable only from the driving side, is
fitted in the partition to the left of the driver. Through this it is possible
to operate from the driver's seat a full-drop outside window. A small sliding
communication panel is fitted in the partition behind the driver. The
driving-compartment door has a lever-operated quick-action full-drop window and
the off-side panel of the deep two-piece windscreen can be opened. Additional
body features include flashing direction indicators; a cab heater, which also
- Sanders patented spherical combustion chamber
system and C.A.V. fuel injection equipment. incorporating the latest
renewable-element paper filter and variable-speed pneumatic governor giving
regulation up to 3.600 r.p.m. at full load.
engine drives through a 9 in. diameter Borg and Beck single-plate clutch with
hydraulic pedal linkage, a three-speed gearbox, tubular propeller shaft and
hypoid bevel rear axle. The synchromesh gearbox has a patented gearchange
control on the steering column and, in conjunction with the axle reduction,
provides overall gear ratios of 16.38, 7.72 and 4.625 to 1. With the engine
governed at 3.500 r.p.m. these provide maximum speeds of about 60 m.p.h. in top
gear, 40 m.p.h. in second and 17 m.p.h. in first gear.
prototype vehicle measures 14 ft. 4 in. long over deep wrap-round bumpers and 5
ft. 4 in. wide. It has a turning
circle of 24 ft. between kerbs. As
tested, with full fuel tank, spare wheel, tools and
- TEST RESULTS AT A GLANCE
Design by Birch Brothers, Limited: chassis by Standard Motor Co, Limited; body
by Park Royal Vehicles, Limited.
Standard 4-cylinder diesel; bore 3 3/16 in
(80.96 mm.); stroke 4 in. (101.6 mm.), capacity 127.68 cu. in. (2.092
litres); compression ratio 17:1; Freeman Sanders spherical combustion chamber
system; 45 b.h.p. at 3,000 r.p.m., 92 lb/ft. torque at 2,000 r.p.m.
Clutch, Borg and Beck 9 in. dia. single dryplate hydraulically operated:
Gearbox, 3-speed synchromesh with steering column control, ratios 3:54, 1:67 and
1:1 forward, 4.11:1 reverse; driveshaft, Hardy Spicer open tubular with needle
roller bearing universals; rear axle, hypoid bevel gear with semi-floating half
shafts. ratio 4.625: 1.
Lockheed hydraulic 11in. by 2 ¼ in., 2 l.s front.
1 ton 9 1/2 cwt. unladen in full kerb trim.
Mainly in Greater London, total distance 212 miles.
Cold to very cold and dry.
WEIGHT: Varying from 1 ton 11 cwt. to
1 ton 15 cwt.
Varying up to equivalent of two passengers and
CONSUMPTION: Overall. 37.2 m.p.g.
GRADIENT CUMBED: 1 in 4 ¼.
CIRCLE: 24 ft. wheeltrack.
DURING TEST: None.
Mean of opposite runs through gears:
Average of measured stops from 30 m.p.h., 37 ft., equivalent to 26 ft. per sec.
Per sec. (0.81 g.) average retardation. Tapley meter readings 90-95 per cent.
TOP SPEED: 60 m.p.h.
supplies warm air to windscreen demisting slots and to the main body through a
closable grill in the partition ahead of the occasional seat; ventilating
windows on each side of the main seats; a red light to warn the driver when any
of the rear doors is not securely fastened; and locks on all doors. The body has
been built to the requirements of Birch Bros. by Park Royal Vehicles, Limited.
- Technical Details
Birch taxi is based on a chassis produced by the Standard Motor Co., Limited,
and is powered by a Standard diesel engine. The chassis has a wheelbase of 8 ft.
5 in. and incorporates linked wishbone and coil-spring independent front
suspension, long semi-elliptic rear springs, piston-type dampers all round, cam
and roller steering, Lockheed hydraulic brakes with tandem master cylinder and
four accessible jacking points for use with the triangulated jack. Although the
5.75-16 tyres are of the tubeless type, a spare wheel is fitted in the luggage
four-cylinder diesel engine is the type which is giving such excellent service
in Birch conversions of London taxicabs and of which there are now 1,500 in
service. Of 2.092 litres capacity, the original high-speed versions of this
engine developed 40 b.h.p. at 3.000 r.p.m. and 85 lb./ft. torque at 50O r.p.m. Recent development has improved the performance and current
engines produce 45 b.h.p. at 3,000 r.p.m. and 91 lb./ft. torque at 2,000 r.p.m.
The engine employs the Freeman
- out 20 lb. of test
equipment, the vehicle turned the scale at 1 ton 9 ½ cwt., of which 16 cwt. was
borne by the front axle. Our test extended over two days and of the total of 212
miles covered, about 150 miles was in Greater London, a good deal of it in short
point-to-point journeys similar to normal taxicab service. The
vehicle proved extremely pleasant to handle and although the pedals had the
appearance of being set at a rather awkward angle, no discomfort was felt after
long periods at the wheel. The steering-column gearchange was straightforward
and positive and the well-chosen gear ratios and freely running engine permitted
performance figures equal to those obtained with a four-speed gearbox in
comparable vehicles. Actual figures obtained, after the speedometer had been
checked and found correct at 30 m.p.h., were 9.8 seconds from rest to 30 m.p.h.
and 18.4 seconds to 40 m.p.h.; these are average figures for two runs in each
direction over a reasonably level road. Top-gear performance also proved lively
and the lazy driver would find he could pull away from 10 m.p.h. in top without
uncomfortable effects and reach 30 m.p.h. in about 13 seconds. Part
of the MODERN TRANSPORT standard test route was covered with the cab to take
advantage of the measured sections and to try the vehicle on the open road. With
a new engine and the governor set rather below the normal maximum, speeds of 58
m.p.h. in top and 38 m.p.h. in second gear were recorded. The engine ran
smoothly and quietly up
- to its maximum and was noticeably quieter at idling
speed than some contemporary diesel installations. Indeed, among the more
outstanding impressions of the vehicle were the almost complete absence of
vibration at all speeds and of a very comfortable ride even on badly paved
roads. These point to a very close attention having been paid to
- from 30 m.p.h. produced an average figure
of 37 ft., equal to an average retardation of 26 ft.. per second per second or
0.81 g. and a result that few vehicles could better.
- Excellent Fuel Economy
with most prototypes, there were a few odd
Birch taxi earns full marks for exception accessibility of the Standard diesel
engine; right, the luggage compartment door hinges on the rear panel to provide
a wide doorway for bulky pieces.
mountings and to the great improvements achieved in suspension systems in recent
- Starting Aid
important modification to the standard diesel engine in this application is the
inclusion of a heater plug to assist cold starting. While we had the vehicle it
was parked out of doors for three nights. On the first morning the outside
temperature was at about freezing point and on the second there was about 6
deg.F. of frost. On both mornings the engine started immediately after about a
30-second application of the heater-plug switch and the setting of the
extra-fuel button on the fuel-injection pump. On the third morning, which was
rather milder, only the heater-plug was used.
suspension and brakes on the vehicle were fully up to modem private car
standards and disposition of the odd loads carried (up to a total of 5 cwt.) in
various positions in the body did not affect control. Even on good surfaces all
four wheels could be locked with reasonable pedal pressure and under these
conditions from speeds around 30 m.p.h. the vehicle pulled up squarely. Measured
emergency stops on dry, level surfaces
- points with which fault could be
found; front comer pillars rather thicker than seemed necessary, outside light
reflected by the glazed partition round the occasional passenger seat after dark
and, we suspect, rather limited leg room even with the adjustable seat right
back for the tall driver. But these are minor points capable of simple
modification if shown to be necessary during service trials.
Birch taxicab makes extremely modest demands on fuel. In our 2I2-mile run, which
included much simulated taxi working in London, overall fuel consumption worked
out at 37.2 m.p.g. An intermediate check carried out on the open road returned a
figure of nearly 40 m.p.g. From these figures it seems reasonable to predict an
average consumption in the region of 34-35 m.p.g. for a vehicle in good
condition employed full-time on taxi work.
and the advantages of improved driver and passenger comfort, together with a
possibly enhanced resale value due to its easy conversion into a useful van or
small multi-seat passenger vehicle, make the new taxicab an extremely attractive
proposition and we have little doubt that the taxicab industry in London and the
provinces will react accordingly.