TB20J Plus Maintenance Manual 35
© Feb. 2023
5 CHASSIS AND TURNTABLE
ASSEMBLY
5.1 CHASSIS AND TURNTABLE
SYSTEM
Chassis Tilt Sensing System
The chassis tilt sensing system measures the angle of
the chassis relative to the horizontal level by means of a
level sensor mounted in the left turntable cover. The
chassis tilt indicator on the platform display panel indi-
cates if the chassis inclination exceeds the maximum al-
lowable tilt angle. When the chassis tilt sensing system
detects that the chassis inclination exceeds the maxi-
mum allowable tilt angle, the chassis tilt indicator will
flash, all movements will be blocked (in the operating
position), the boom will be allowed to retract and lower
and the turntable will be allowed to rotate slowly (in the
non-operating position).
Travel Drive System
This machine adopts four-wheel drive. The four-wheel
drive system consists of one closed-circuit variable-dis-
placement pump, four variable-displacement plunger
motors, four travel reducers and one travel control
valve. The drive speed depends on the closed-circuit
variable-displacement pump, engine speed and motor
displacement. Full-time control is applied for traction
control. The drive function is limited by the position of
the boom tube. See Page 35, Travel Speed Reduction
System for details.
Travel Speed Reduction System
When the boom is in the operating position, the travel
speed of the machine is automatically limited to the op-
erating speed.
Reverse Drive Confirmation System
The reverse drive confirmation system warns the opera-
tor of the situation that may cause the machine to travel
and steer in the direction opposite to the travel direction
of the joystick. The reverse position indicator on the plat-
form controller indicates such situation. When the boom
is positioned between the two rear wheels, the system
does not impose any restrictions on the travel of the ma-
chine. If the boom is positioned beyond any rear wheel
while the machine is traveling, the reverse position indi-
cator will flash, and the machine's driving and steering
functions will be blocked. To restore the driving and
steering functions, press the reverse position travel
drive switch on the platform controller, then the reverse
position indicator will be lit, indicating that the driving
and steering direction of the machine is opposite to the
travel direction of the joystick.
Outrigger Oscillating System
If the machine is equipped with oscillating function, it
must have outrigger oscillating system. Both the front
axle and rear axle are connected to the chassis by shaft,
and the telescoping action of the oscillating cylinders on
both sides of the front axle is controlled by the oscillating
multi-way valves behind the chassis. If there is relative
displacement between the chassis and the rear axle,
the oscillating multi-way valve will be triggered and start
to control the oscillating cylinder to perform correspond-
ing telescoping action. This action does not require aux-
iliary electrical components for detection, nor does it be
subject to any conditions, and oscillating in all working
conditions can be achieved. So, the machine’s four
wheels can always contact with the ground even when
driving on rough and uneven ground, which greatly im-
proves the trafficability and operating comfort.
5.2 TIRE ASSEMBLY
Check Tires and Rims
Check the tires and rims daily and replace the tire if any
of the following defects is found:
• The tire is severely cracked, broken, deformed or
has other abnormalities.
• The tire ply has a smooth, uniform cut with a total
length of more than 75mm (3in).
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