SAFARI

23 POWER STEERING 2. Checking for oil leaks: The control valve must fully activate in order to be able to determine the leakage oil in the steering system. For this reason a minimum of approx. 200 N (20 kg) must be applied to the steering wheel. The test is carried out with the pump running and a pressure is set on the steering test ing rig which l ies approximately 20 bar below the maximum pressure given on the type plate. The maximum permissible leakage oil under these conditions is 8 LPM for type M 033. The test can be carried out with blocked steering drop arm or in the end position of the cylinder. Repeat the leakage oil check at a pressure of 20 – 30 bar. 1. Checking the valve setting: The pump is running and the oil circulates through the hydraulic system of the steering unit. No counter force is set on the steering input shaft on the steering test rig. The torque measuring tool (Tool no. 4) is turned slowly to both sides up to the stops in each case and the device is released several times during this process. The steering must not move in any direction on its own.The difference in the torques when steering to left and right must not exceed 30% in respect of the low value up to a pressure of 3 bar compared with the flow pressure when the steering drop arm is blocked 2. Checking control valve: Close the control valve by turning the steering wheel then build up the maximum pump pressure. The steering wheel should then be slowly released. The valve should then return to the 0 position, i.e. the oil pressure must fall to the flow pressure. 3. Checking the seals: No leaks should be visible on the hydraulic steering unit after running for 10 minutes in the neutral position of the steering valve. Tightness at high pressure must be determined during the test in accordance with points 2 to 4 of this section. Place the dust seal (1.1) on the segment shaft up to the shoulder, applying HTR2 grease or equivalent between the dust seal and housing, and place the protective cap (70) on the steering spindle end, applying HTR2 grease or equivalent between the protective cap and valve housing. X Fitting the steering unit in the vehicle Note: In order to ensure perfect functioning of the ZF hydraulic ball & nut steering, special emphasis must be paid to cleanliness when fitting all the relevant units of the system and when laying the oil lines. In order that faults can be avoided due to foreign bodies or dirt in the oil steering circuit the cap plugs on the line connections of the steering unit, oil pump, working cylinder, valves etc. should only be removed when connecting on the lines. Connection lines and securing elements must be carefully cleaned and debarred. 1. Clean any paint or dirt from the contact faces of the mounting brackets. 2. Insert the steering gear in the mounting bkts and tighten the bolts with the corresponding torque. 3 Stresses which may occur during the assembly of the steering gear/bearing block due to the position of the dash board or on the circumstances when securing the steering column tube and steering spindle. Stresses can cause bending forces especially in the steering spindle which, depending on size and frequency, may lead to fractures or impair the easy movement of the steering gear. To check whether the steering unit has been installed correctly should be carried out as follows: 3.1 Check the movement of the steering gear at the mounting bracket, steering drop arm and drag links (s). Fit the universal joint or the flexible coupling between the steering column and the steering gear.The angled fork section must be at right angles to the markings on the steering spindle and steering columns tube or valve housing in straight ahead position. The angle should be the same if two joints are used and the joint forks must be arranged in one plane. If it is not possible to fit them in this way, synchronization can be achieved by positioning the forks on the serrated gearing in respect of each other. Hammer blows on the joints must be avoided in the case of aluminium universal joints because this might lead to destruction or stiffness. Connect them by