Lucas Industries, at the London Motor Show, is exhibiting one of the most unusual and technically advanced vehicles in the world today - a purpose-built, front wheel drive, battery electric taxicab.
LUCAS INDUSTRIES DEMONSTRATED THEIR FRONT WHEEL DRIVE BATTERY ELECTRIC TAXI CAB. TOP SPEED APPROX 55 MPH. A RANGE OF 100 MILES, THESE CABS ARE BUILT TO MEET THE SPECIFICATION OF THE LONDON METROPOLITAN POLICE PUBLIC CARRIAGE OFFICE. IT IS POLLUTION FREE, WASTES NO ENERGY WHEN STOPPED IN TRAFFIC HOLD UP,: EASY TO HANDLE IN RESTRICTED SPACES
THE 50 B.H.P. 216 VOLT C.A.V. ELECTRIC MOTOR IS MOUNTED TRANSVERSELY IN FRONT OF VEHICLE. BATTERY PACK (LIGHT WEIGHT HIGH ENERGY DENSITY LEAD ACID BATTERIES).
TAXI'S (DIESEL) WITH EXHAUST FUMES PASSENGERS ALIGHT FROM CAB C.U. PETROL VEHICLE EXHAUST.
Weight and dimensions
Lucas Electric Taxi#London Taxi
Length#140.5 in.#3.57 metres#180.5 in.#4.58 metres
Width#69.5 in.#1.77 metres#68.5 in.#1.74 metres
Height#70.0 in.#1.78 metres#69.5 in.#1.77 metres
Track - front#60.5 in.#1.54 metres#56.0 in.#1.42 metres
Track - rear#59.5 in.#1.51 metres#56.0 in.#1.42 metres
Wheelbase#94.0 in.#2.39 metres#1110.6 in.#2.81 metres
Weight of prototype#2,250 kg.#1,600 kg.
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Background: Lucas Industries, at the London Motor Show, is exhibiting one of the most unusual and technically advanced vehicles in the world today - a purpose-built, front wheel drive, battery electric taxicab.
With a top speed of approximately 55 mph, a projected range of around 100 miles on a single charge, and rapid recharging by battery exchange, the Lucas electric taxi suggest how the distinctive image of the car might evolve in the last quarter of the century.
Two prototype Lucas electric taxis have been built to meet the specification of the London Metropolitan Police Public Carriage Office, from which guidance has been obtained, and they have the same excellent turning circle as present London cabs.
Advice and comment has been obtained from the taxi trade during the development of the vehicle. In addition, cab drivers have driven the prototypes and have offered constructive criticism.
The attractive body-styling and lively performance of the Lucas electric taxis will compel immediate interest from the bystander. The body, designed and built for Lucas by Ogle, was evolved to minimise the overall dimensions and to keep down drag and weight to accomplish maximum utilisation of the energy available from the lightweight Lucas lead-acid batteries.
The compactness of the vehicles is such that five Lucas electric taxis would be able to park in a rank which four London taxicabs would normally occupy.
The two prototype vehicles will be used as mobile test beds for the evaluation of their Lucas drive systems and the other Lucas technology involved. Progressive refinement will be carried out in the light of experience, and running costs will be established.
One Lucas electric taxi may be seen on the Ogle Stand (Stand 74). The other will be used for demonstration runs during the period of the Earls Court Show.
FIRST LUCAS PURPOSE-BUILT ELECTRIC VEHICLE
Until now, the Lucas electric vehicle research and development programme has utilised standard vehicles converted to battery electric operation.
The first electric vehicle to be introduced was a 34-passenger Midi-bus based on a Seddon chassis which went into service in Manchester city centre in February, 1975.
In the Summer a fleet of converted Bedford CF vans was delivered to the Post Office, in London, for evaluation on mail delivery and telecommunications work. A luxury personnel carrier, based on the van chassis, was demonstrated at the Paris Salon.
The electric taxi Phase Three is the first Lucas purpose-built vehicle in the programme. Experience gained in developing electric vehicles suggested to Lucas that taxicab operation might be a good application for electric vehicle systems.
There are a number of factors in its favour.
It is relatively inexpensive to run. The fuel cost for electricity is a fraction of the cost of diesel oil (although battery replacement cost must be taken into consideration). Generally, battery electric vehicles require less maintenance than their diesel or petrol unguent counterparts.
It is pollution-free.
It is also extremely quiet. This could be a boon to residents in urban areas, particularly at night.
And taxi duty, with a good deal of stopping and starting, particularly suits the electric vehicle. The Lucas electric taxi wastes no energy when it is stopped in a queue of traffic.
GREATER COMFORT ALTHOUGH SMALLER
The Lucas taxi will carry the same number of passengers as the present London cab but in greater comfort since the internal dimensions are more generous.
Externally, the vehicle is only a little longer than Mini Traveller marginally less in width than a Jaguar and it is approximately the same height as a London taxicab.
The driving position combined with the panoramic windscreen offers the driver a view that has possibly not been equalled since the days of the Hansom cab.
A novel feature is the fixed driving seat with control pedals which are adjustable to accommodate drivers of different heights in comfort.
The 50 bhp 216-volt CAV motor which drives the taxi is located transversely at the front of the vehicle, level with the floor of the driving compartment. The motor drive is transmitted to the differential by low-loss,double reduction. Morse HY-VO chains giving a 5.63:1 drive ratio. A short quill shaft, between the reduction chain drives, provides a degree of shock absorption between the motor and road wheels. The chains are spray lubricated by a small oil pump driven by an extension of the quill shaft. The pump draws oil from a sump below the second chain casing where the differential is located.
From the differential, power is transmitted to the road wheels by short drive shafts fitted with constant velocity joints. Although the cab is front wheel drive it has the excellent turning circle for which the London taxi is renowned.
The complete front drive until assembly, consisting of the motor, chain reduction drives, differential unit, oil sump, brakes and road wheels, is carried on a sub-frame which can be detached as a unit from the vehicle.
All of the road wheels are carried on low-los SKF bearings.
The Lucas developed control system is of the SCR chopper type, a sophisticated means of transferring the battery output to the motor.
The controller operates by connecting and disconnecting the power source to the motor through a solid state (SCR) switch so rapidly -- a few hundred times a second - that the motor 'sees' only the average of the resultant 'chopped' voltage.
By changing the ratio of the open to closed times of the switch, the average voltage across the motor is varied. Additional solid state circuitry automatically adjusts the power to the motor so that it is appropriate to the driver's demand and the vehicle speed.
The battery pack is carried in a detachable tray located under the vehicle floor. Although the pack can be charged in situ with appropriate equipment, it can also be readily exchanged for a new pack, if necessary. The process would take no longer than refuelling a conventional vehicle. The pack uses the same type of lightweight high energy density lead-acid batteries as is employed by Lucas in its other projects.
Drawing on its long experience in the field, Lucas has considered many types of batteries, but holds the view that the lead-acid type is capable of further development to meet the power needs for the new generation vehicles.
A typical traction battery gives some 10 watt-hours per pound of battery weight at the two-hour discharge rate, the unit having a life expectancy of around 1,500 useful charging cycles. The normal, hard rubber, SLI (starting,lighting and ignition) battery gives about 12 watt-hours per pound weight at the two-hour rate, and 100 traction cycles.
Polypropylene SLI batteries such as the Lucas Pacemaker give 13.6 watt-hours per pound at the two-hour rate.
To achieve a competitive electric vehicle, a low-cost high energy density battery is required. The Lucas approach has been to take the polypropylene SLI design as a starting point and improve its cycle life to an acceptable level whilst at the same time making further advances in the energy/weight/volume ratios.
The current research programme is aimed at producing a battery with a life of several hundred cycles.
Fully independent, coil spring from wheel suspension is provided. The rear wheel suspension is by a split beam axle located by trailing links and a Panhard rod.
The body is a fully floating monocoque of thin gauge steel sheet and bonded GRP (glass fibre) mounted on a box steel perimeter chassis which houses the battery tray and the battery.
Impact absorbing bumpers are fitted front and rear to minimise parking damage, with bolt-on replaceable body corners to facilitate inexpensive repairs.
Tinted glass is fitted all round for comfort and privacy.
The body was designed and built by David Ogie of Letchworth.
A Girling servo-assisted hydriodic braking system is fitted to the vehicle. In addition, to extend the operating range and to minimise wear and tear on the mechanical brakes, a regenerative braking system is employed. This utilises the kinetic energy of the vehicle to drive the traction motor during deceleration. Under these conditions, the role of the motor becomes that of a generator acting as a form of electric transmission brake which provides a degree of charge to the batteries. By this means some of the energy which is normally absorbed in breaking is instead returned to the battery. Greater braking than is available from the motor is provided by the Girding hydraulic brakes which are brought into operation by further depression of the brake pedal.
Apart from the drive system,the taxi is fitted with other Lucas equipment such as head, side and tail lamps, horn, switches and windscreen wiper motor. A Kienzle electronic taxi meter is also provided, and this is installed in the dashboard with a repeater fitted on the transparent bulkhead (or partition) of the passenger compartment.
The auxiliary 12-volt battery which powers these items is charged by a special high efficiency converter unit which is fed from the traction battery. This makes it unnecessary to change the auxiliary battery when the main traction battery is exchanged.
Vehicle heating is accomplished by means of a combustion heater which can be switched on before the taxi goes into service, ensuring comfort in winter for driver and passengers-even on the first run of the day.