THRUST SSC HYDRAULIC CONTROL OF ACTIVE/PASSIVE SUSPENSION
Early in 1995 we were approached by Jeremy Bliss of the Thrust team and asked to help put into practice the ideas he had for controlling the suspension of a car at speeds up to 750 mph. This we did and subsequently supplied 12 customised manifold blocks along with financial sponsorship for the project.
The hydraulics are used solely to control the suspension. It is a sealed system fitted with two pumps, one engine driven and one standby driven by electric motor. Pump pressure is controlled via a ventable relief valve.
The suspension system consisted of three parts:
Passive This was fitted to each of the wheels and replaces the springs and dampers normally fitted on a family car. Oil is allowed to flow to and from gas springs (accumulators) across a series of needle valves that control the rate of damping. Relief valves were used to remove any sudden shock sensed by the suspension. Adjusting the hydraulic pressure on each wheel predetermined the hardness/softness of the ride.
Active This was on the rear wheels only and was used to alter the attack angle of the car during the run. A computer profile linked to the Mach number, altered the displacement of the active part of the suspension struts via an hydraulic servo control valve.
Failsafe This was also linked to the rear wheels only and was used if the run was aborted or the supply from both of the hydraulic pumps should fail. A reserve of oil, under pressure, was held in two large accumulators, primed externally prior to each run. The pressure from the pumps was sensed onto a number of diverter valves. If this pressure dropped below a certain value the diverter valves switched extending the struts to a predetermined position, moving the car to a ‘safe’ attitude. This was then held until the car was brought back under control.
For further information or assistance with hydraulic requirements, please contact:
STERLING HYDRAULICS LTD, Sterling House, Crewkerne, Somerset, TA18 8LL
Tel: (01460) 72222 or fax (01460) 72334. Email: [email protected]