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The Smithson Trolley-bus Controller

17th March 1933, Page 89
17th March 1933
Page 89
Page 89, 17th March 1933 — The Smithson Trolley-bus Controller
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ASIMPLE form of control gear which is particularly suitable for trolley-buses. is marketed by J. G. Smithson and Co.; Nelson House, Moor Street, Birmingham. The controller-is designed for use with motors up to-150 h.p., and its Weight is just over 100 lb:, whilst the overall dimensions are 25 ins, by 12 ins. by 12 ins. • Inside a-cast-aluminium casing there is a row of Smithson patent trigger-operated contacts. Each pair of contacts uses only two moving parts, and by means of an overcentre arrangement the opening and the dozing of the contacts is very 'rapid. The actual. contact surfaces are made of Steb metal, which consists of a -coppervbase on to which -a heavy silver face is attached by sweating and roiling. By the use of silver the life of the contacts is greatly increased.

• Another feature of interest is that the contacts, when opening or' closing, are given a slight rolling motion combined with a wiping action. The latter, although its movement is only some .002 in., is sufficient to avoid any possibility of the contacts being welded together. On the mechanical side durability is ensured by the fact that the two moving parts

are suspended on knife edges' and are spring-loaded, so y

thaany wear which may take place is automatically taken up.

In the complete controller there are eight contactors for plain series control, together with one or two field-shunting notches. Each contactor is closed by a simple lever, without the aid of cams or ratchets. Actually, the mechanism is remarkably simple, for the eight or 10 levers lie in a row and are depressed in sequence by a lever or blade of insulating material which is coupled to the control pedal. Although quite free from complications, this gives light and positive operation, whilst each notch can be distinctly felt as the succeeding contactors are brought into action.

A hole is formed in one end of the easing and through this the cables are carried direct to their respective terminals. These are of heavy brass and are mounted on an insulated terminal board, to which is fixed a plate giving the marking of each control. Mounted inside the casing is a quickly detachable unit which includes the arc shields and the blow-out coils. By removing this unit the contact surfaces can be examined Without difficulty.

Reversing is effected by means of a separate drum-type switch consisting of an insulated moulding in which the contacts are inserted. The stationary contacts are mounted on hinged fingers, compression springs being used to provide the necessary pressure. This switch is interlocked electrically with the main controller and is encased in sheetsteel covers with east-iron end-plates. All metal parts in the controller and the reversing switch which are at all liable to corrode are zinc coated by the metalization process, or, in the case of some of the smaller parts, are cadmium plated.

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Locations: Birmingham

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