<342EC1B6C7E2C0E5C4A12E717864> (EN)

GROUP 3 OPERATIONAL CHECKS AND TROUBLESHOOTING GROUP 3 OPERATIONAL CHECKS AND TROUBLESHOOTING This procedure is designed so the service man can make a quick check of the steering system using a minimum amount of diagnostic equipment. If you need additional information, prefer to structure and function in group 2. A location will be required which is level and has adequate space to complete the checks. The engine and all other major components must be at operating temperature for some checks. Locate system check in the left column and read completely, following this sequence from left to right. Read each check completely before performing.

At the end of each check, if no problem is found (OK), that check is complete or an additional check is needed. If problem is indicated (NOT OK), you will be given repair required and group location. If verification is needed, you will be given next best source of information : Chapter 2 : Troubleshooting Group 4 : Tests and adjustments 4-16

Стр. 1

Hydraulic oil must be at operating temperature for these checks. 4-17 Item Description Service action Steering unit check Run engine at low idle. Turn steering wheel until frames A are at maximum right (A) and then left (B) positions. B LOOK : Frames must move smoothly in both directions. When steering wheel is stopped, frames must stop. FEEL : Excessive effort must not be required to turn steering wheel. NOTE : It is normal for steering to drift from stops when steering wheel is released. OK Check completed. NOT OK Go to next check. Steering system leakage check Heat hydraulic oil to oper- ating temperature. Run engine at high idle.

Turn steering wheel rapidly until Right frames are against stops. Left Hold approximately 2kgf on steering wheel. Count steering wheel revolutions for 1 minute. Repeat test in opposite direction. LOOK : Steering wheel should rotate less than 5rpm. NOTE : Use good judgment; Excessive steering wheel rpm does not mean steering will be affected. OK Check completed. NOT OK Do steering system leak- age test in group 4 to isolate the leakage. Priority valve in steering va l ve l ow p r e s s u r e check Park machine on a hard surface. Hold brake pedal down. Run engine at high idle. Steer machine to the right and left as far as possible. LOOK :

Machine must turn at least half way to the right and left stops. OK Check completed. NOT OK Do steering system leak- age test in group 4 to isolate the leakage. Priority valve in steering valve high pressure check Run engine at high idle. Steer to steering stop and release wheel. Roll bucket back and hold over relief and observe engine rpm. Turn wheel to steering stop and hold, observe engine rpm. LOOK : Steering stall engine rpm must be higher than hydrau- lic stall rpm. OK Check completed. NOT OK Do steering valve pres- sure test in group 4.

Стр. 2

2. TROUBLESHOOTING 2. TROUBLESHOOTING Diagnose malfunction charts are arranged from most probable and simplest to verify, to least Diagnose malfunction charts are arranged from most probable and simplest to verify, to least likely, more difficult to verify. Remember the following steps when troubleshooting a problem : likely, more difficult to verify. Remember the following steps when troubleshooting a problem : Step 1. Operational check out procedure (see group 3 in section 1) Step 2. Operational checks (in this group) Step 3. Troubleshooting Step 4. Tests and adjustments (see group 4) 4-18 Problem Cause Remedy No steering Low oil level. Restricted suction line. Failed hydraulic pump.

Stuck priority valve spool. Broken priority valve spring. Relief valve in priority valve stuck open. Failed hydraulic lines. Add recommended oil. Check. Remove and inspect return filter for metal pump particles. Remove and inspect priority valve spool. Remove and inspect spring. Do relief cartridge leakage test. Check. Slow or hard steering Too much friction in the mechanical parts of the machine. Cold oil. Low priority valve pressure setting. Worn hydraulic pump. Sticking priority valve spool. Broken priority valve spring. Pinched or restricted LS line. Low system relief valve setting. Low overload relief valves setting.

Lubricate bearings and joints of frame or cylinders or repair if necessary. Check steering column installation. Warm the hydraulic oil. Do priority valve pressure test. Do hydraulic pump performance check. Remove and inspect. Remove and inspect. Inspect line. Do priority valve LS port flow test in group 4. Test and adjust if necessary. Test and adjust if necessary.

Стр. 3

4-19 Problem Cause Remedy Constant steering to maintain straight travel Air in system. Leakage in steering system. Worn steering unit. Leaf spring without spring force or broken. Spring in overload relief valve broken. Gear wheel set worn. Cylinder seized or piston seals worn. Check for foamy oil. Do steering system leakage check. Do steering unit neutral leakage test in group 4. Replace leaf springs. Replace overload relief valve. Replace gear wheel set. Replace defects parts. Slow steering wheel movement will not cause any frame movement Leakage in steering system. Worn steering unit gerotor. Do steering system leakage check. Do steering unit leakage check.

Steering wheel can be t u r n e d w i t h f ra m e s against steering stop Leakage in steering system. Do steering system leakage check. Steering wheel turns with no resistance and c a u s e s n o f r a m e movement Broken steering column or splined of steering unit. Lack of oil in steering unit. Leakage in steering system. Remove and inspect. Start engine and check steering operation. Do steering system leakage test in group 4. Erratic steering Air in oil. Low oil level. Sticking priority valve spool. Loose cylinder piston. Damaged steering unit. Check for foamy oil. Add recommended oil. Remove and inspect spool. Remove rod to inspect piston. Remove and inspect.

Spongy or soft steering Air in oil. Low oil level. Check for foamy oil. Add recommended oil. Free play at steering wheel Loose steering wheel nut. Worn or damaged splines on steering column or valve. Tighten. Inspect. Steering unit binding or steering wheel does not immediately return to neutral when released Binding in steering column or misalignment of column. High return pressure. Contamination in steering unit. Inspect. Check for a pinched or damaged return line. Inspect hydraulic fi lter for contamination. Repair cause of contamination. Flush hydraulic system.

Стр. 4