COUPLING 9X3690 - Caterpillar

Increasing the air spring pressure increases the percentage of the total machine weight carried by the mid-rollers. Increasing the air spring pressure can give the following benefits:Provide better steering performance, especially under load.* Improved ride, due to the mid-rollers absorbing a greater amount of the shock loads.An air spring with insufficient pressure causes poor turning performance under load and increased roughness of ride.Depending on the type of equipment, soil conditions, and performance requirements, the optimal spring pressure may vary from 410-620 kPa (60-90 psi). Various pressures should be tried to find the optimal setting for the particular situation. Do not exceed 650 kPa (95 psi) regardless of weight on the machine.Service Brake System and Parking Brake
Service Brake System Schematic
(1) Hydraulic oil tank. (2) Charge pump (service brake boost). (3) Service brake pedal. (4) Fluid reservoir. (5) Master cylinder power booster. (6) Service brake master cylinder. (7) Multiple disc inboard brake. (8) Bleeder valve assembly.The components of the service brake system are: master cylinder power booster (5), service brake master cylinder (6), charge pump (service brake boost) (2), service brake pedal (3), service brake fluid reservoir (4), and multiple disk inboard brake (7) located in the steering differential group.The system has two different hydraulic circuits: a service brake circuit to operate the multiple disk brake and a charge (service brake boost) circuit that hydraulically assists the master cylinder power booster to reduce service brake pedal effort by the operator.The service brake system is equipped with bleeder valve assembly (8) to remove air from the system.When the engine is running, charge pump (service brake boost) (2), fastened to the steering pump, takes oil from hydraulic tank (1) and sends it to master cylinder power booster (5).When service brake pedal (3) is not pushed, power booster flow is unrestricted through power booster (5).As the operator pushes service brake pedal (3) the power booster restricts the output flow which increases the power booster pressure that multiplies the force from the pedal linkage connected to power booster (5).Master cylinder (6) then begins to send fluid to multiple disc inboard brake (7). The fluid sent to the multiple disc inboard brake either stops or slows the machine down.Fluid reservoir (4) supplies makeup fluid for master cylinder (6). SAE 0W-20 oil is recommended. If SAE 0W-20 oil is not available, Mercon/Dexron Automatic Transmission Fluid (ATF) can be used for a substitute.Master Cylinder Power Booster
Master Cylinder Power Booster (NEUTRAL Position)
(1) Passage. (2) Power piston. (3) Relief valve. (4) Connector. (5) Return. (6) Inlet. (7) Piston. (8) Spherical rod end.The oil from the charge pump (service brake boost) enters the master cylinder power booster through inlet (6).Relief valve (3) is set to open when the pressure behind power piston (2) reaches 655 kPa (95 psi).The linkage from the service brake pedal is connected to spherical rod end (8). When the service brake pedal is pushed for brake application, the brake linkage moves spherical rod end (8) and piston (7). As piston (7) moves forward, it restricts