Power Steering Pump


Pump for power steering – high power   Art.no: Unic 392X-03
(Used where large servo power is needed, eg if the steering is heavy at fast steering angles or at high loads as in tracked curves)


— Deplacement: 6.5 cm3/rev.
— Oil pressure: Normally 100 -140 Bar  (base setting of pressure reliefe valve = 120 Bar). The pressure releife valve can also be set to a requested pressure. The pump is dimensioned for up to 250 Bar.
— Pulley for Multi belt PK-6. Outer diameter Ø132 (measured over rib top’s).     — Alternativ Pulley for Multi belt PK-5  Outer diameter Ø153.
— Connections: Thread R 3/8″ female in both in & out ports.
— Filter unit with interchangeably filter. Connections 2x AN 8.


Additional technical info:
— Recommended ratio between the crankshaft pulley and pump = 1.4  ± 8%  This mean the outer diameter of the crank pulley (measured over the rip top’s) = Ø94 ± 8% with pulley Ø132 and Ø110 ± 8% with pulley Ø153. Too high rev. can damage the pump.
— Recommended hose dimensions:
Pressure line between pump and steering rack = Ø6mm.
Return from steering rack to tank through filter unit = Ø8mm (filter must be used).
Feeder line between tank and pump = min Ø10mm (also through the connectors).
— Recommended tank volume: 0.5 liter  min.
— Oil cooler is normally not necessary due to the high efficiency of the pump.
— The setting of the pressure relief valve can be changed if needed. The pressure level is dependent on factors such as the piston area in the steering rack, the ratio between the steering rack and wheel (length of the control arms…) , caster angle and  while also other suspension geometry influences but although not as much.
— Pump efficiency coefficient:  mechanic ~0,9  ,  volymetric ~0,9
— Torque on the pump shaft at 100 bar = 6.5 x 100 / 20 / 3.14 / 0.9 = 11,5 Nm.
— Used power at 100 bar and engine speed 6000 RPM = 11,5 x 6000 / 9550 / 1.4 = 5,1kW (ie peaks that occur during cornering).
— The average power consumption at fullspeed on track (supercar) = approx. 2.2 kW (based on average pressure of 50 Bar and engine rev.5000 rpm). When the car is in full acceleration the pressure is usually low (<15 bar) and therefore the pump uses low power (< 1 kW).


– Keep in mind that a bad pump “steals” more power even if the servo effect is worse.  In motorsport the poorer efficiency coefficient in standard pumps (vane pumps) makes the oil warmer and thinner, and thus the efficiency is even lower, i.e. a vicious circle. Hot oil increases wear and also the risk of rupture of hoses and seals.  The higher effiency in this pump results in an oil cooler if mostly not needed.