Two New Battery electric Models A ' STEERING head incorporating the
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power unit and transmission is a feature common to all the battery-electric vehicles manufactured by Scott Electric Vehicles, Ltd., Kidderminster. The latelt additions to the range are a 1-ton light-delivery chassis intended mainly for export, and a dray tractor for the railways.
The motor for I-ton vehicles develops 2 h.p., and a 1 i. h.p. unit is available for TO-cwt. vehicles intended for use in hospitals, light industrial undertakings and so on. Compound or series winding is employed according to requirements, and the motor can he supplied as a dual unit with a switch for changing from compound to series. In any of the applications, the complete power head may be replaced by a spare unit in less than an hour.
Compound-wound Motor.
The value of the compound-wound constant-speed motor is that it prevents overspeedineunder easy conditions by acting as a brake when there is any tendency to exceed the normal maximum m.p.h. This is a particularly useful characteristic When installed in the light-delivery vehicle, the maximum speed of which is 10 m.p.h. fully laden. In this application the motor runs on a 36-volt 160 ampere-hour battery, which gives the vehicle a range of .30 miles: the maximum gradient climbable with a full load is 1 in 8.
All motors have a three-step controller supplied by Sharp Control Gear, Ltd., Ashby-de-la-Zouch. They are built to Scott specifications by the Normand Electrical Co., Ltd., Clapham o m in on,London, S.W.4. For industrial, work, the speed of the motor is reduced from 2.000 r.p.m. to 1.000 e.o.m., and the vehicles can climb gradients of I in 6. In this case the motor operates on a 24-volt, 160 ampere-hour battery; chain gearing gives a reduction ratio of 3 to 1.
The power head turns in the frame on rollers, which are adlxted by
eccentric pins. Suspension is provided by four coil springs and the unit tilts slightly, in the direction of turn. thus reducing chassis stresses to a minimum. The angle of turn is limited to 180 degrees' so that the current can he supplied by flexible cables instead of slip rings. A switch is fitted for reversing.
The road-vehicle chassis has an electrically welded frame consisting of foto. 4-in. by 2-in, by channel section steel members, quarter-elliptic rear springs designed to. withstand a 50 per cent, overload, and a rear axle with Timken-hearing hubs and internal expanding brakes. The tyres are 18-in. by 7-in. pneumatics. , The dray tractor which was specially developed for inside use, has a particulady high seat position, which reduces the efforts of the driver when unloading as he is enabled to step across to the dray without dismounting. The tractor is used with the standard 13-ft.-type of dray, with which it forms an articulated unit having a turning circle of 24 ft. 6 ins. A 2 h.p. compound-wound industrial power head, draws current from a 184 ampere-hour battery.
The front axle of the dray is lifted off the ground by a hydraulically actuated table with power operation supplied by a small electric motor driving the pump.
With or without dray the maximum speed of the tractor is 4 m.p.h., and it can tow a dray with a I-ton load up a gradient of 1 in 10. The tractor has a wheelbase of 7 ft. 7 ins, and the platform is 3 ft. 4 ins. wide. Including battery its weight is 1 ton 1 qr. The battery is mounted on rollers for ease of withdrawal, and it is stated that the capacity is sufficient for a 9-hour shift with about 25 per cent. in hand.
Other vehicles ip the range include
trailer tractors for and 2-ton loads, elevating trucks with handor power' operated platforms, and fixed-platform trucks, which are available with variou body lengths. The tractor and fixed. platform truck are supplied with solid or pneumatic interchangeable tyres. and both have quarter-elliptic rear springing. With compound-wound motors the operating speed is 5 to 6 m.p.h., a serieswound motor giving a speed of 8 to 10 m.p.h. 'f he table of the elevating truck has a 4-in, lift and can be raised in 7 secs. by hand and in 3 secs. when power operated.