MAINTAIND 800 BATTER ELECTRIC!
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By I... J. COTTON THERE are few problems in electric-vehicle maintenance that cannot be readily solved by Silent Transport, Ltd., Woking, which is responsible for the upkeep of 800 battery-electrics • of all classes and makes. Mr. W. M. Scully, the general manager, has been with the concern since it first commenced operations in Guildford in 1941, when he was made responsible for 189 of these vehicles and had a staff of six fitters to maintain them.
By 1946 the concern was responsible for more than 700 vehicles and had outgrown the Guildford works, and a move was made to larger premises at Woking. The new works, having additional space, permitted the erection of a paint shop, as well as the other sections required for the complete maintenance of a vehicle. Previously a certain amount of the work had been "farmed out," a process which was not entirely satisfactory.
Woking is now the headquarters for the supply, overhaul and documentation of this large fleet, which is spread over the whole of the British Isles. All 'the vehicles have been supplied through Silent Transport, Ltd., and a record card is maintained at Woking for each machine from the time of its delivery to the operator. This card contains details of the make, type and capacity of the vehicle, date of supply to the operator, and battery and electrical data. A further column is used to record the date on which the vehicle is due back at the works for overhaul. '
A Supervisor for 15 Vehicles A trained employee is appointed to take charge of a batch of 15 vehicles. Sometimes these are located in the same garage, or in other cases where they are run by several operators the vehicles are nominally grouped into an area. It is the responsibility of the resident fitter to maintain these vehicles in accordance with the normal weekly, monthly and quarterly service schedules, and to make a full report to the operator and headquarters on all work carried out. Servicing is detailed on forms provided for the various routine periods, and in this manner the entire history of the vehicle is maintained. c4 As the battery is the most expensive item, and the one that will rapidly deteriorate through misuse or neglect, care is taken to ensure that it receives adequate maintenance. Initially, the charger relay which is supplied with the vehicle is set correctly for the battery, and the vehicle is never connected to a different charger. Each battery has its own characteristics and must be treated accordingly; Weekly Maintenance of the battery consists of checking the level of acid and topping up with distilled water until the spray arresters are covered. Terminals are tightened and cleaned if necessary, new grease being used when the terminals are reconnected. Hydrometer readings are taken and recorded to give some indication of the condition of the battery.
Weekly Tyre Check
Tyre pressures are checked weekly. This is important, because low pressures would increase the tractive effort of the vehicle, with consequent reduction .in its range. Brakes, steering and axle nipples are greased at this period, and the level of oil in the rear axle is checked. Should the brake system be of hydraulic pattern, the fluid is topped up if necessary and the vehicle taken on a short road test to check the efficiency of the brakes..
It is important that the brakes should be effective, because, unlike the petrol-engined vehicle, the batteryelectric relies solely on the brakes to retard its speed when travelling downhill. Furthermore, poor brakes would present a problem to the driver when parking the vehicle at each point throughout his round.
At the end of each month the battery is given an equalizing charge. Failure to carry out this procedure would cause the plates to harden and capacity to be lost. The vehicle is thoroughly lubricated at this period, and the steering-box lubricant checked. All electrical equipment is thoroughly inspected, and maintenance of the controller gear follows one of three methods, according to the equipment employed in the vehicle The electrically operated controller with snap contacts is simple to service, because the main wear takes place at the cdntroller tips, which are readily accessible when the control panel is removed. It is important that the timelag • mechanism, fitted to some of these models, should operate correctly. Fluid used in the hand or foot control bucket has to be checked and topped up. Should any defect occur at this point it would cause the contactors to burn, also damage the driving motor and bring about ultimate transmission failure.
Drum or rotary-pattern controllers, because of the comparatively slow action and the drag which takes place each time they are operated, suffer a certain amount of arcking. This causes wear and burns away the sector unless the controller is serviced at regular intervals. Again, should the contacts be neglected, transmission failure may occur as a result of a contact not functioning.
The mechanically operated snap-pattern controller provides a quick make-and-break circuit in a similar manner to the electrically operated type. It is essential that the time-control mechanism should function correctly and that the contact fingers should receive attention. If necessary, the contact fingers may be changed in two to three minutes, Commutator and brush gear of the motor are inspected for burning or wear. Some brushes have a high rate of wear, and unless they are changed at the requisite interval they may cause damage to the commutator. In that event the motor would have to be dismantled so that the damaged surface could be
machined. The commutator is cleaned at regular intervals, which are determined from the monthly inspection. Armature windings are examined (so far as the inspection cover will permit) to ensure that the solder is intact. Any slight indication that the soldering is breaking away is investigated and the motor stripped.
Mechanical details are covered by the monthly service, the whole chassis being lubricated, oil levels in the steering box and rear axle topped up, and the springs sprayed with oil. Brakes are adjusted for wear, U-bolts checked for tightness and front-wheel alignment tested Any mis-alignment will not only cause damage to the tyres and steering mechanism, but will also increase the tractive effort of the vehicle, thus shortening its range. All this work is carried out on the operator's premises, and reports on the condition of the vehicle and work done are sent to Woking The quarterly inspection, which covers the whole of the vehicle, is again recorded on a form, a copy of which is sent to the operator as well as to headquarters.
This inspection report is split up into 14 sections, representing the major assemblies of the van. First the front axle and steering are inspected for wear, tightness
and alignment, and answers to the following six questions are recorded:—Are springs and shackles in order, holding-down bolts tight, steering joints serviceable, hubs in order, wheels in alignment, steering box in order. A statement on the wear of the king-pins and brakes is also required.
The motor and transmission are then inspected and observations made in answer to seven to nine queries, according to the make of chassis. This examination deals with the condition of the motor, cables, securing. bracket, propeller shaft or chain transmission, and, in the case of the °raiseley, condition of the clutch and gearbox.
Controller contacts, connections and fixings then come under the eye of the inspector, together with resistances, speed steps and reversing and isolating switches. The next stage is the rear-axle inspection, in which the unit is checked for wear, oil leaks and security of bolts and hubs.
The brakes are tested for wear, and an estimate made of the useful life of the facings, and brake cables and cross-shafts are examined for undue play. The level of hydraulic fluid in the gravity tank is topped up. Next the body is inspected, and here the paintwork, doors, upholstery and panels receive attention. The inspector further safeguards the operator by checking details on the licences, holders and number-plates.
Battery and crate are then examined and a record is made of the specific gravity of any ten cells of the battery, followed by an observation on its capacity to meet the requirements of the daily work.
The normal vehicle electrical equipment, including horn, windscreen wiper, lighting, wiring and charger socket, is checked for correct operation While dealing with the electrical equipment the charger is checked, together with the cable and plug connecting it to the vehicle.
Thorough Examination
Next the tyres are examined and pressures recorded, and at the same time the wheel nuts are tested for tightness. The chassis is examined for cracks or loose rivets and the findings recorded. The remainder of the inspection deals with the accessories to the chassis and body and the general condition of the vehicle.
Repairs requiring to be done immediately are recorded on a separate form for the urgent attention of the operator and headquarters.
At yearly intervals the vehicle is returned to headquarters for revarnishing or painting and overhaul. This overhaul, which may take from a week to fortnight, is completed at an average cost of £50, and to assist the operator a similar vehicle is lent to him while his own is in for repairs. At ibis period the motor is dismantled and tested, new bearings fitted if required, chassis wiring tested, and the electrical gear thoroughly overhauled.
A new battery is ordered for the vehicle at the end of three years. This is a precautionary measure, and the battery is not fitted until the original is found incapable of performing the day's work As in the case of petrol vehicles, the driver of the battery-electric can lighten repairs by careful driving. Drivers who have had previous experience on petrol vehicles are inclined to accelerate rapidly from a standstill and tend to ignore any time-delay mechanism which may be fitted. This practice is detrimental to the batteries and transmission, the batteries suffering from high discharge rates and the transmission from the high torque which, in a battery-electric, is greatest at stalling point.
Count Steps in Accelerating To move a 1-ton vehicle away from rest 350 amps. are required. This rate can be raised to 500 amps. on sharp acceleration, which, although lasting for only a second, is sufficient to take a toll of the battery. A driver who has been initially trained on a battery-electric usually drives it in the advocated manner and counts the steps between the contacts. If he finds that he is missing a stage in the contacts he immediately reports the fault to the resident fitter. By this means the defective contact is traced and rectified before any damage is caused to other parts of the electrical gear or transmission.
A good driver will avoid using the brakes as far as
possible on level ground. The vehicle should be accelerated half the distance between stops spaced at 200-yd. intervals, and permitted to coast the remainder of the distance. By this process the capacity of the battery will be conserved throughout the day.
When travelling downhill, the speed should be restricted to the maximum speed of the vehicle on level territory. With the low axle ratio of the battery-electric, running at excessive speeds downhill will set up high centrifugal forces in the motor. Should any of the armature windings break free, it would be thrown out and tear away the coil windings