Propel Brake Interlock Valve
Propel Brake Interlock Valve.
(1) Propel brake interlock vale.
Propel brake interlock valve (1) prevents the operator from
propelling the machine while the parking brake is applied. The
valve prevents the pump swashplate from moving out of
neutral when the parking brake is applied.
The valve has a solenoid on one end to move the valve spool.
When the parking brake button is in the RELEASE or OFF
position, the valve spool shifts to block the lines between the
servo pistons. Charge oil can now be directed by the servo
valve to one end of the servo piston to move the swashplate
When the parking brake is in the ON position, the valve spool
connects both sides of the servo piston. This equalizes the
pressure between both servo pistons and prevents the servos
from moving. The oil from the servo piston is open to case
drain and goes back through the control valve.
Thermal Bypass Valve Group
Thermal Bypass Valve Group.
(1) Cooler port. (2) Thermostat. (3) Inlet port. (4) Passage.
The bypass valve group directs returning hydraulic oil flow from
the drive motors to either the hydraulic oil cooler or tank.
When the temperature of the hydraulic oil reaches 71 C
(160°F), thermostat (2) begins to open and the hydraulic oil
has a split flow to the oil cooler and tank. When the hydraulic
oil temperature to inlet (3) is over 85°C (185°F), the thermostat
fully opens and the hydraulic oil goes through cooler port (1) to
the oil cooler. When the return oil pressure, in the bypass
valve group, reaches 345 kPa (50 psi) bypass relief valve will
open and allow the return oil to go directly to the hydraulic oil