Kubota KX080-4 Workshop Manual page 134

KX080-4, WSM
[D] Parking Brake
[E] Auto-Decelerator Function
• This function gives priority to power for traveling and when the mini-excavator is traveling in the 2nd speed, if the
travel load becomes great, such as when climbing or turning, it automatically decelerates to 1st speed
(low-speed). When the load is low, it returns to the 2nd speed (high-speed).
• When the speed button on top of the blade lever is pressed, it actuates the solenoid of the unload valve, thus
guiding oil from the pilot pump to the 2-speed port (1). When pressure oil flows to the 2-speed port, it moves the
ridged spool (2) to the right.
• Conversely, when the load (a) on the motor rises, pressure is guided against the small area of the ridged spool
(2), overcoming the pilot pressure and pressing the ridged spool (2) to the left, which releases the oil in chamber
S (5) to the drain via the ridged spool.
• The parking brake is a negative brake composed of
a rotating disc (friction material) (4), an opposing
plate (5) a brake piston (3) and a spring (1).
• When the travel motor is stopped (the travel lever in
neutral), the parking brake takes effect.
• The cylinder block (6) and the disc are linked via a
spline and a friction material is applied to both sides
of the disc. The disc is spring-loaded and friction is
generated between the flange holder and the brake
piston, and this limits the force with which the motor
can turn, allowing it to function as a parking brake
• When pressurized oil is guided into the brake piston
chamber (2), it generates an amount of thrust that
matches the area of the brake piston that receives
the pressure and overcomes the spring, thus moving
the brake piston. The disk rotates freely between the
flange holder and the brake piston, eliminating the
parking brake function.
(1) Spring
(2) Brake piston chamber
(3) Brake piston
3-M38
HYDRAULIC SYSTEM
(4) Disc (friction material)
(5) Opposing plate (plate)
(6) Cylinder block
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(1) 2-speed port
(2) Ridged spool
(3) Spring
(4) 2-speed switch piston
(5) S chamber
(6) Swash-plate
(7) Ball
(a) Motor load pressure
(b) Drain
(c) High pressure selector
valve
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KiSC issued 08, 2015 A