Hydrosteer
From Wikipedia, the free encyclopedia
Hydrosteer was the name given by George Kent Ltd and Cam Gears Limited through Hydrosteer Limited[1] of Luton, England, to its automotive power steering system. Initially Hydrosteer manufactured the Ross-Link system for commercial vehicles from 1953 under licence from Ross Gear and Tool of U.S.A.[2] Their own product available from 1961 was based on a cam and peg system and was characterised by its fully integrated design and variable steering ratio. This configuration provided automotive manufacturers with a fairly simple design modification to provide a power steering option for cars fitted with a conventional cam and peg steering box. It was fitted to several, mainly British, luxury automobiles of the era. Production continued up to 1973, with just over 105,000 units being produced. As a "first generation" assistance system, applications were somewhat varied in their tuning of the many system dynamics to the specific vehicle. The system fell out of use as powered rack and pinion steering systems gained in popularity.
The 1960s Hydrosteer system should not be confused with Hydrosteer Pty Ltd, an Australian company established in 1981 as a provider of heavy truck steering technology in that country.
The Hydrosteer power steering system was fitted to the following cars:
Austin Westminster A110 (optional)
Facel Vega II (optional)
Humber Super Snipe Series V (optional)
Humber Imperial
Rover P5 3-Litre Mark 1a (optional)
Rover P5 3-Litre Mark 2 Saloon and Coupe
Rover P5 3-Litre Mark 3 Saloon and Coupe
Rover P5B 3.5-Litre Saloon and Coupe
Austin Princess DM4 Limousine(optional)
Vanden Plas Princess 3 Litre Mk II (optional)
Vanden Plas Princess 4-Litre R
Wolseley 6/110 (optional)
Operation
[3] The Hydrosteer system was based on a conventional cam-and-peg mechanism, except that the cam is surrounded by the skirt of a piston within the body of the steering box. Hydraulic power from the power steering pump is transmitted directly from the piston to the peg carrier. A spool type hydraulic valve moves along the axis of the cam in response to steering wheel movement, causing oil pressure to be applied to one side or other of the piston according to the direction the steering wheel is turned, and the load on the input and output shafts.
The cam track is not a regular helix but varies in pitch angle and depth. The variation in steering ratio between straight ahead and full lock results from the variance in pitch angle of the track. The more the steering wheel is turned, the lower the steering ratio becomes. In the Rover P5B, for example,[4] the ratio of the power steering unit was 16:1 at the straight ahead and 11.3:1 at full lock.
The effect of the variable ratio is to give very light and relaxed steering at the straight ahead, with increased reaction when cornering. The system was designed to be fail-safe, so that the driver should still be able to steer in the event of a failure of the power system.