Power Assist Steering | Pinion Valve Repair |
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The power assistance of steering (hereafter, PAS) is operated by the oil pressure of hydraulic system. The flow distributor (hereafter, FD) supplies the oil pressure to the PAS system as long as main suspension and braking system hydraulic circuit works with certain oil pressure. If the oil pressure to the latter circuit goes down by some reason, the FD stops to provide the oil pressure to the PAS hydraulic circuit. It brings on "non power-assisted steering". The hydraulic system of the BX gives priority to the braking and suspension system.
When the main system and FD function normally, the oil pressure from FD is distributed from the steering pinion gear and control valve (= pinion valve) to two chambers of the power cylinder. The power cylinder is operated by the oil pressure right and left at the steer, and the steer power is assisted.
Pinion valve is divided into 3 rooms with 5 oil sealings and distributed hydraulic oil passes through each room. If the 3 sealings inside of them are deteriorated, those 3 rooms will not be divided well. Consequently, feeling of steering becomes very heavy as if it were freezed. It comes on the one side; we have some user's reports on the left side. Last symptom is typical model caused by deteriorated sealings.
When you feel steering heavy anytime, it is not easy to specify the cause. It happens by the deteriorated flow distributor, the power cylinder, steering gear...etc.
If the oil sealings which are at the top and bottom of the pinion valve become worse, LHM oil will leak from there. Concerning the top side, you can check the leakage by eyesight. However, leakage from the bottom side occur in the rack. In this case, LHM oil may leak from the steering rack gaitors.
Refer to this section about the removal of the pinion valve.
(C) Yohsuke NARABAYASHI
Translate: Tomio NOGUCHI