Grace's Guide

British Industrial History

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Humphris Gear and Engineering Co

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of Eastleigh, Hants

1908 Humphris Gear 'Instead of the usual toothed wheels, there is a large, circular plate in which circular slots are cut in which run the transmitting gear. According to whether the gears are running in the train of holes near the centre or near the outer circumference of this plate, so accordingly the speed becomes slow or fast. It is claimed for the Humphris gear that there is less slip, greater strength, and less wear in this form of transmission than in any other.'[1]


The 1907 design had moved the large driving plate sideways in order to allow the pinion to be moved from one series of thimbles to the other

1908 Humphris Patent Engineering Co, of Piccadilly, London, showed a 15 hp chassis at the Motor Show. In this design the large plate was fixed, and an ingenious device drew the pinion on one side before the gear lever slides it backwards or forwards for the change of speed.

On the 15 h.p. chassis the suspension was arranged so that no unsprung weight is carried by the live axle casing, nor can any side strains be thrown on the springs. This is effected by tying a rear transverse spring to the frame with a parallel motion given by two diagonal rods pinned at top and bottom to two arms, one on each side, each pinned centrally to a bracket on the rear portion of the frame, the rear transverse spring being bolted in the centre to a lug on the gear casing of the live axle, with the two ends jointed to the lower portions of the arms to which the diagonal rods are applied.

The engine is mounted on an underframe, which extends past the clutch to form an attachment for the torque tube that encases the propeller shaft. This underframe is carried in the main frame on two trunnions fitted on the horizontal transverse line of the centre of gravity of the unit. The torque is therefore thrown on to the trunnions, and when the rear wheels bump over an uneven surface the slip on the tyres is practically nil, owing to the very long length of the radius connection, which is, of course, that between the rear axle and the trunnions. For a movement of the springs equal to 7in. vertically, the slip with rigid tyres would be 3/64ths of an inch, which is so small that it could be taken by the yielding of the rubber. Seven inches movement on the springs would break them, but the figures are useful as an illustration. We shall be interested to see how these claims are borne out by performance on the road.

1908-09 Made a few experimental cars and may have sold one

See Also

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Sources of Information

  1. Daily Telegraph & Courier (London) - Wednesday 18 November 1908