GPO Vehicles

General description of facilities
This vehicle has a forward control cab equipped with seating accommodation for three passengers and a driver, under seat lockers and two under floor compartments for the storage of a Generator, Reed Hummer and the vehicle tool set.  A sliding door separates the cab from the body which is fitted with thermal insulation, side windows, roof ventilators, cable access flaps on either side of the rear door, a paraffin heater with an external flue (see H 0030), lockable cupboards, interior lighting, apparatus benches, a 12V d.c. power supply and floor-mounted lashing anchorages.  Two skirting lockers are provided on the near-side of the body for the storage of petrol and paraffin containers and an off-side skirting locker is provided to accommodate the spare wheel.  A detachable towing fitment provides facilities for towing a trailer tool cart when necessary.  This vehicle is intended for use on cable balancing duties and, because of the expensive interior fittings, it should not be used as a general stores carrier.

Taken from - ENGINEERING INSTRUCTIONS, TOOLS & TRANSPORT,  VEHICLES, N 3080 (Issue 1, 23.11.66)

A New Cable Test Van
By G. Slater
Taken from the POEE Journal Volume 47 October 1954

The author describes a new cable test van which gives improved accommodation for test equipment and facilitates testing operations in the field. An important development is the inclusion of a satisfactory heater unit for maintaining suitable atmospheric conditions within the van.

Introduction
The Test van was one of the first, if not the first, of the motor vehicles in the Engineering Department fleet, excluding, of course, one or two passenger cars, and a brief reference to the original test van which was brought into service some 40 years ago will serve as an appropriate introduction to the subject.

This vehicle, shown in Fig. 1, was obtained in 1914 for the Research Section for the purpose of testing telegraph and telephone underground trunk cables, and no doubt the testing of the London-Birmingham-Liverpool trunk cable laid in 1914-15 was one of the main factors in mind at that time.

In 1919 only two test vans were in operation, but with the development of the underground cable trunk network and the devolution of cable testing and balancing from the Research Section, the number had increased to 14 by 1927 and to 29 by 1935. To-day the Department has in service some 70 test vans, one of which is shown in Fig. 2, and except for changes in chassis types and methods of body construction, no major changes in the layout of the vehicle have occurred over a period of some 25 years.

Fig. 1. The First G.P.O. Cable Test Van; Built in 1914	Fig. 2. Type of Cable Test Van in General Use To-day

That improvements were necessary to facilitate testing operations was apparent as far back as 1938, and immediately prior to the war a redesign of the test van was commenced. The development had then to be suspended for the duration of the war, and although work recommenced in the immediate post-war period, material and financial restrictions made progress slow. The maintenance of existing test vans in service much beyond their normal period of service was therefore necessary.

Features of the New Test Van
The provision of a dry atmosphere inside test vans to ensure that the electrical insulation of the apparatus is maintained at the level necessary for accurate testing has always been a difficult problem. Various ways of disposing of condensation on the apparatus have been resorted to in practice, none of which was really satisfactory. The locations in which test vans operate preclude the use of mains power for electrical heaters; heaters which are dependent on heat derived from the vehicle engine are also precluded, since the vehicles are required to be stationary for very long periods during the testing operations and to run the engine during these periods would be costly. The use of heaters independent of mains supply and the vehicle engine, such as the usual type of paraffin heaters, has the disadvantage that the combustion products project additional moisture into the atmosphere of the van, thus tending to defeat the object of disposing of the condensation inside the vehicle and on the testing apparatus. A catalytic heater has also been considered. This flameless heater, using petrol as the fuel in conjunction with a platinised asbestos pad, proved to be unsatisfactory in operation as it produced carbon monoxide.

A means of producing the required atmospheric conditions was eventually evolved at the Research Station, using a paraffin heater, and a specially designed flue to carry off the products of combustion to the outside atmosphere. Heaters of this type have now been incorporated in the design of the new test vans (Fig. 3) recently put into service and have also been fitted to all existing test vans which have a reasonable length of unexpired service.

Fig. 3. The New Cable Test Van

Fig. 4.  Interior View of New Cable Test Van Showing Heater and Flue

The heater, fitted in the body of one of the new vehicles, is shown in Fig. 4. It consists of a heavily constructed fuel container with a capacity of 1 gallon, which is sufficient for 16 hours burning. A double gauze cylinder surrounds the chimney of the heater which is housed immediately beneath
a baffled flue, rectangular in shape and constructed of aluminium alloy. The flue terminates on the outside of the vehicle in a cowl which effectively prevents down-draughts. The heater is capable of producing some 10,000 B.T.U., equivalent to 2.9 kW per hour. The fire risk has been reduced to a minimum; indeed, the heater may be left burning whilst the vehicle is in motion and in garages overnight, thus ensuring a body interior free from condensation in readiness for the day's testing operations. The fuel supply for the heater is carried in two 1 gallon cans which are accommodated in a locked compartment situated outside the vehicle on the offside beneath the floor.

A feature which has been introduced, but which is not obvious from the appearance of the vehicle, is greater heat insulation of the vehicle body effected by the use of a heat-insulating material packed in the space between the outer aluminium alloy and the inner plywood body panels.

Ventilation is controlled by adjustable louvred vents at floor level and ventilators in the roof, which, together with the improved type of adjustable side windows, should ensure adequate natural ventilation reasonably free from draughts.

The rearranged benches provide adequate space for the testing gear and have been simplified by dispensing with the folding facility which, it was found on investigation, was rarely used. The fence rail at the edge of the benches has been improved. It is now produced in light alloy and arranged in sections to facilitate raising and lowering. This, it is hoped, will be of considerable advantage when it is necessary to dispose of the uncomfortable ridge when a section of the bench is used for writing purposes - a discomfort which was often endured in the old vehicles because of the awkwardness of lowering the one-piece rail.

The bench tops have been finished in green linoleum and incorporate the necessary test lead holes and a cable entry flush-fitting flap.

Beneath the benches two cupboards have been arranged, one at the rear of the offside with a hinged door, and one with sliding doors towards the nearside forward end of the body. The cupboards are fitted with adjustable shelves and provide adequate space for stowing equipment. The wheel arches have been squared off and fitted with fence rails to provide additional under-bench stowage space.

Above the offside bench a light alloy rack extending practically the whole length of the body affords convenient accommodation for storing test sheets and the records associated with testing operations. The edge of the rack is padded to provide protection for the head in the event of accidental contact whilst moving about the vehicle.

Interior lighting is provided by battery-operated pendant-type lamps arranged above the benches and a roof light above the rear step. The sets of lights on either side of the body are controlled by separate switches placed at the forward end of the body and the step light by a switch conveniently placed adjacent to the rear door. On each side of the vehicle, immediately above each bench, a conveniently placed plug socket gives access to the 12V battery supply for testing purposes and, should it be necessary, for a portable bench light.

The provision of ring bolts in the floor, apparatus-securing straps on the benches, and concertina-type blinds to the windows completes the internal equipment of the body of the vehicle, which is finished in green and cream, giving the whole a pleasing appearance and a serviceable finish.

Fig. 5.  Built-In Steps at Rear of New Cable Test Van

Access to the rear of the vehicle, which incorporates a full-width sliding window in the door, has been considerably improved by the introduction of a built-in step (Fig. 5) which, when not in use, folds into the body of the vehicle. On either side of the rear door two cable entry traps give access to the interior of the body.

The forward control chassis on which the vehicle is built enables much improved cab accommodation to be provided. Seating for four persons, including the driver, is available; bucket-type seats for the driver and the front passenger and a bench seat, facing forward and located on the offside of the cab, for the rear passengers. The driver's seat is adjustable for height and in the forward and rearward directions. A view of the cab is shown in Fig. 6. Beneath the rear passengers' seat are two spacious lockers, which are independently locked, providing ample personal locker space and, if required, additional stowage space for equipment.

Fig. 6. Sliding Door Opened to show Interior of Cab of New Cable Test Van

Access to the body of the vehicle from the cab is by means of a sliding door (Fig. 5) which is fitted with a Yale type of lock to ensure the security of the contents of the body when the vehicle is left unattended in garages with the cab doors unlocked. A sliding glass panel fitted in the bulkhead partition provides a clear line of vision from the cab, through the body and the large window in the rear door, to the rear of the vehicle. The two 12-V vehicle batteries, provided to cope with the heavy lighting load which occurs when testing operations necessitate the interior illumination of the body, are located beneath the cab in an under floor locker, access to which is obtained via a floor trap secured by a budget lock.


Accommodation for the Generator No. 2 (Reed Hummer) is provided in a compartment also beneath the cab floor immediately below the front passenger seat. Access to this locker is obtained through a floor trap uncovered by tipping the passenger seat forward. The compartment is felt-lined to provide a reasonably soundproof housing for the Generator No. 2, and has been located in this position so as to be as remote as possible from the test benches within the body of the vehicle. Wiring for connecting the generator is terminated inside the compartment and extends in conduit to a terminal block mounted above the offside test bench.

The vehicle tools, with the exception of the jack handle, are accommodated in another under floor locker beneath the driver's seat, access to which is gained by sliding the seat forward. The jack handle is housed on the rear passengers' seat supporting rail where it is secured in position by two straps. Two coat hooks, one on either side of the sliding door aperture, and a light for illuminating the cab complete the cab facilities. Access to the cab is gained by a flush-fitting sliding door on the nearside and by a hinged door for the driver on the offside.

To provide for towing a trailer tool cart a detachable towbar was specially designed by the Motor Transport Branch. This towbar slips into two vertical key ways fitted to the ends of brackets which are attached to the rear of the chassis members. When not required the towbar is housed beneath the chassis on the offside along with the spare wheel, access being gained by means of a hinged flap which when closed completes a deep unbroken skirt line for the vehicle body.

Mounted as it is on a well-sprung chassis with adequate shock absorbers, the vehicle is considered to be a considerable improvement on the old type of test van, and it is hoped that it will serve the users well.