To enable brake force to be adjusted correctly by catching any change in the height of a vehicle body frame as a change in a load by providing an electronic control means for applying the output from a vehicle floor height sensor to a brake liquid pressure control means only when a brake operates so as to set a brake fluid pressure.
Brake liquid flows out from the fluid entrance 11 of a load sensing proportional valve 2 to a fluid exit 12 through the hole 10 of a balance piston 9 and a gap between a valve seat 13 and a poppet valve 14. And, since the fluid pressure on the fluid entrance 11 side increases, while the fluid pressure on the fluid exit 12 side stays constant, the balance piston 9 is pushed downward by this differential pressure, the poppet valve 14 separates from the valve seat 13 at a position in contact with a rod 16 so that the brake fluid pressure may be increased. In this case, an output signal from a vehicle floor height sensor is impressed on a solenoid 18 and the position of the rod 16 is adjusted to the vehicle floor height at the time of starting brake operation. Namely, initial setting of brake fluid pressure is properly applied in response to a load.
SHIGEMI YOSHIHIDE
CHIYOU AKITAKE
TAKADA MASAHIRO
