Kubota KX080-4 Workshop Manual page 127

KX080-4, WSM
[D] Parking Brake
[E] Hydraulic Timer
a)When the parking brake is operated
• When the brake release pressure is interrupted,
springs press the brake piston (1) against the disc (2)
that meshes with the spline on the circumference of
the cylinder block (3).
• Friction holds the cylinder block (3) to the case,
preventing it from turning.
(1) Brake piston
(2) Disc
b)When the parking brake is released
• When the brake release pressure is guided to the
brake piston chamber (1) via the PG port (P), the
release pressure acts against the resistance of the
brake piston's spring, eliminating the friction with the
disc and allowing the cylinder block to turn freely.
(1) Brake piston chamber
• The hydraulic timer is a function for preventing drag
on the parking brake when the swivel brake is used
and it plays the role of ensuring delayed timing so the
parking brake does not operate while hydraulic
dynamic braking is absorbing inertial energy from the
turning of the swivel; the delayed timing is achieved
via flow control through an orifice that slows the
discharge of oil from the brake piston chamber (1).
• From the state of the motor turning, when the pilot
valve returns to neutral, the pilot valve switch signal
and the linked timer valve switch pressure SH go to
low pressure, and the brake piston chamber (1) and
drain port (3) are linked by the spring (2).
• The pressure on the brake piston chamber (1)
moves it in the direction to allow it to press against
the disc via the force of the spring acting on the brake
piston, but as flow is restricted by the timer valve
orifice, until a certain amount of time passes, the
brake piston does not touch the disc and the parking
brake does not engage.
(1) Brake piston chamber
(2) Spring
(3) Drain port
3-M31
HYDRAULIC SYSTEM
(3) Cylinder block
RY9212148HYM0032US0
P: Port PG
RY9212148HYM0033US0
(a) ON
(b) OFF
RY9212148HYM0034US0
KiSC issued 08, 2015 A