Yamaha YP250A 1999 Supplementary Service Manual page 15

ABS OUTLINE
S Hydraulic control valve
Hydraulic control valve is composed of the sole-
noid valve and flow control valve.
1) When the normal brake is applied, the solenoid
valve closes 2 , the spool 3 of flow control
valve does not move and the hydraulic line be-
tween the master cylinder and brake caliper is
opened.
2) While the ABS works, the solenoid valve 2 is
supplied the power to open when the electronic
control unit signals the pressure reduction and
the spool 3 of flow control valve is moved to-
ward to the solenoid valve.
3) When the electronic control unit stops the sig-
nal of pressure reduction, the solenoid valve
2 closes and pressurizing starts again. Re-
pressurizing while the ABS works controls the
flow of brake fluid by the movement of spool 3
of flow control valve, and provides slow pres-
sure rising.
1 Orifice
2 Solenoid valve
3 Spool
4 Flow control valve
S Buffer chamber
Accumulates the decompressed brake fluid tem-
porarily while the ABS works.
1 Buffer chamber (in normal state)
Buffer chamber (decompressing)
2
3 Raise the piston
7
GEN
INFO