MAINTENANCE 4.11 EVERY 500 OPERATING HOURS OR MONTHLY 4.11.4 CRAWLER TRACK - INSPECTION CHECK ADJUSTING RANGE OF GUIDE WHEELS (Track retensioning range) GENERAL The hydraulic track tensioning system, illust. Z 20371 maintains automatically the correct track tension. The pilot pressure oil of the travel brake release circuit is used, to pressurize the four adjusting cylinders (10) and (11). The resulting force moves the guide wheels toward the front, until the correct track tension is obtained. External forces acting upon the guide wheels are absorbed through the pressure accumulators (8A) and (8B). Legend for illust. Z 20371:
(1) Rotary distributor (2) Supply line, pilot pressure from travel brake release circuit (3) Return oil line (leakage oil) (4) Valve block (5) Pressure relief cock for hydraulic track tensioning system.
“C” - Closed (Normal working position) “O” - Open (6) Shut-off cock in supply line “O” - Open (Normal working position) “C” - Closed (7) Two stage pilot pressure operated relief valve (8A) Pressure accumulator, high pressure (150 bar) (8B) Pressure accumulator, low pressure (31 bar) (9) Shutoff cocks, RH & LH “O” - Open (Normal working position) “C” - Closed (10) Track adjusting cylinders, inner (11) Track adjusting cylinders, outer (12) Test connectors and vent valves Before working on the hydraulic track tensioning system, relieve all pressure in the system by opening cock (5), posi- tion ’0’. After finishing the service work close the pessure relief cock (5), position ’C’. 361 WARNING