TM 5-3805-260-24STEERING CONTROL VALVE WITHRELIEF VALVE OPEN4. Flow control valve. 5. Pilot valve. 7. Orifice.When the pilot valve opens, oil flows through orifice(7) and past the pilot valve. The flow of oil past theorifice causes a lower pressure in the chamber for theflow control springs. This lets the pressure of the oil inthe inlet passage move flow control valve (4). Oil frominlet (2) can flow through the holes in the flow controlvalve. This releases the extra pressure from the circuit.When the outside force is gone and the pressure isreduced, the flow control valve and pilot valve return totheir normal positions.Left Turn PositionThe control valve operation for a LEFT TURN is similarto that for a RIGHT TURN. When the steering wheel isturned to the left, the valve spool moves into the valvebody. Pump oil, from the inlet, flows through the slotson the valve spool into outlet (1 I). This oil then flows tothe cylinders and a LEFTTURN is the result.The cylinder pressure is felt through passage (12), andagainst the pilot valve and flow control valve. The rest ofthe relief valve operation is the same as a RIGHT TURN.TROUBLESHOOTINGThe 5P5224 Pressure Gauge Kit can be used tomake the pressure tests of the steering system. Beforeany tests are made, visually inspect the completehydraulic stem for leakage of oil and for parts that havedamage. For some of the tests a magnet and ameasuring rule (either for inches or millimeters) areusable tools.WARNING: When testing and adjusting thesteering system, move the machine to a smoothhorizontal location. Move away from personnel andmachines that are at work. There must be only oneoperator. Keep all other personnel away from themachine.VISUAL CHECKSA visual inspection of the steering system and itscomponents is the first step when a diagnosis of aproblem is made. To remove the tank filler cap, slowlyturn the filler cap until it is loose. If oil comes out thebleed hole, let the tank pressure lower before the fillercap is removed. Make the following inspections:1. Measure the oil level.2. Check for air in the hydraulic oil. Do thisimmediately after the machine has been operated (%with the engine still running). Use a clear bottle or’container to get a sample of the oil in the hydraulic tank.Check the sample to see if there are air bubbles in theoil.3. Remove the filter elements and look for particles.removed from the oil by the filter element. Amagnet will separate ferrous particles from non-ferrousparticles (Piston rings, O-ring seals, etc.).4. Check all oil lines and connections for damage orleaks.PERFORMANCE TESTSPerformance tests of the steering system can be usedfor a diagnosis of poor performance and to find thesource of oil leakage inside the hydraulic system. The oilmust be at the normal temperature for operation whenthe tests are done.PROBLEMPROBABLE CAUSERECOMMENDED CORRECTIVE ACTIONSteering wheel hard to turn.1. Mechanical linkage does not move freely.2. Valve spool does not move freely in its bore.a. Check mechanical linkage, repair or replaceas necessary.b. Check valve spool, repair or replace asnecessary.2-111
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