Hydrostatic Transmission Giving Two-pedal Control
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WHEN a Hydrocar I-ton industrial truck was demonstrated by The Plessey Co., Ltd., last Friday, it was claimed that the Hydro-stabil infinitely variable hydrostatic transmission fitted to the truck provided an appreciable saying in fuel consumption (as well as ease Of control), a highly favourable low speed torque and ample braking power.
As announced in April this year, the Plessey company are licensed to _manufacture the Hydro-stabil equipment in a range covering capacities from 2 h.p. to 125 h.p. and to market the equipment throughout the British Commonwealth.
The vehicle demonstrated was equipped with a hydrostatic transmission system housed in the back axle. This comprises a variable delivery pump and two fixed delivery motors, which drive the rear wheels through spur gears giving a reduction of 6.7 to 1. Both the pump and motors are of the axial-piston type. The cylinder barrel of the pump is mounted on trunnion bearings, so that its axial position relative to the input shaft can be
adjusted manually to provide variations in the stroke of the pistons and, therefore, in output. In the case of a back axle assembly of a similar type, designed for an input of 22 b.h.p. at 2,200 r.p.m., the rated maximum torque output is 2.380 lb. ft. at 24 r.p.m.
Use of the system eliminates the need for a clutch, reverse gear or differential, and braking power is sufficient to lock the rear wheels without friction .brakes. Th system is controlled by two " rocking " pedals giving forward and reverse, the rear wheels being locked when the pedals are in the neutral position. In a demonstration of the Hydrocar on a ramp having a gradient of 1 in 4, it was shown that the transmission affords exact "
inching" control down to virtually zero speed without snatch or judder.
Friction brakes are fitted in the axle assembly for parking purposes and to satisfy the Regulations. The propeller shaft housing is employed as a cooling system for the fluid.
Transporter , Bridge Celebrations ikAIDDLESBROUGH'S transporter IV-1bridge will be 50 years old on October 17, and Middlesbrough Corporation transport committee has decided that it should be illuminated to mark its jubilee. Mr. F. Lythgoe, general manager of the transport department (which is responsible for the bridge), is also to investigate the possibility of lighting the top of the bridge structure, nearly 200 ft. high.
Two Extra Vehicles
AT Edinburgh on Monday, Mr. John M. Rennie, of South Queensferry, applied to vary a B licence by the addition of two vehicles of 61 tons "road and building materials within 25 miles." Hiring in the area had become increasingly difficult as a result of the work on the Forth Road Bridge, the approach roads, and the new B.M.C. factory at Bathgate, it was pointed out.
Mr. Ivo Townsend, the Deputy Licensing Authority, granted two vehicles solely on the existing Forth Road Bridge work within a 15-mile radius.
I.R.T.E. OFFICERS THE following office hearers have been elected by the Institute of Road Transport Engineers for the forthcoming year: President, Sir William Black (chairman. A.E.C., Ltd.), vice-president. Mr. J. H. Vincent (technical officer, London Carriers, Ltd.); Hon. Sec., Mr. G. Curtis (inaintenance engineer, Borough of Wembley"); Hon. Treasurer; Mr. A. Enticknap (managing director, Alpha Motors. Ltd.); Hon. Advisory Officer, Mr. R. Hastings (chief engineer, transport. Park Royal Transport, Ltd.).