FRAME GP 9W7552 - Caterpillar

Hydraulic Starting System
SCRAPER ENGINE STARTING SYSTEM
1-Start valve (mounted on scraper engine gauge panel). 2-Quick release valve. 3-Start valve (mounted on tractor dash panel). 4-Drain port to hydraulic tank. 5-Valve spool. 6-Control valve group. 7-Air chamber assembly. 8-Pinion. 9-Ejector control lever. 10-Air supply line. 11-Air supply line. 12-Oil drain line. 13-Oil filter. 14-Hydraulic cranking motor. 15-Clutch assembly. 16-Air chamber assembly. 17-Hydraulic cranking motor oil supply line. 18-Hydraulic cranking motor oil drain line. 19-Flow control valve.With the tractor engine running and scraper controls in HOLD position, the air and hydraulic pressures at the scraper engine are great enough to actuate the scraper engine starting system.The hydraulic cranking motor is interconnected with the scraper ejector hydraulic system. The ejector must be in the returned position for a sufficient amount of oil to be available to rotate the cranking motor.The starter system for the scraper engine is actuated by depressing button (1) or (3). Pressure air is then released to the top of air chamber assemblies (7) and (16). Air from the tank exerts a force on the diaphragm in chamber assembly (16) and mechanically moves lever (9) to return position. At the same time, air actuates air chamber assembly (7), moving valve (5) and engaging the cranking motor pinion with the flywheel ring gear.When control valve (6) is fully opened, oil flows through line (17), control valve (6) and cranking motor (14), then returns through line (18) to the flow control valve (19).Pinion (8) is connected to the cranking motor through over-running clutch (15). When the diesel engine starts, this clutch will disengage.The system includes a check valve in flow control valve (19). This valve prevents reverse rotation of the starting motor when the ejector is being operated. If any oil does get past the check valve, line (12) directs it back to control valve (6) and out port (4) to return to the hydraulic supply tank. Line (12) is blocked by valve spool (5) when the starting system is actuated.
HYDRAULIC CRANKING MOTOR GROUP
4-Port to hydraulic tank. 6-Control valve group. 7-Air chamber assembly. 12-Oil drain line. 14-Hydraulic cranking motor. 20-Hydraulic oil outlet port. 21-Hydraulic oil inlet port.When the start valve is released, the pinion disengages, the control valve closes, and the ejector control lever will return to the HOLD position.Air Valve Assembly
AIR VALVE ASSEMBLY
1-Push button. 2-Plunger. 3-O-ring seal. 4-Valve. 5-Seal. 6-Port to air reservoir. 7-Spring. 8-Port to air chamber assemblies.An air valve assembly (start valve) controls the air supply to the air chamber assemblies located on the ejector control lever and on the cranking motor group. Air is supplied from the air reservoir to port (6) where it is blocked by valve (4). Valve (4) is held closed by spring (7).When button (1) is depressed, it pushes plunger (2) against valve (4), opening the valve. This allows air from port (6) to pass through port (8) to the air chamber assemblies. When the button is released, springs behind plunger (2) and valve (4) return the respective parts to the normal (closed)