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B. Working principle of lifter
Fig.4-20 is a working principle diagram of position adjusting of the lifter (with simple
direction exchange valve and high adjustable performance). While pulling the operation
handle (10) to lowering position, position locating steel ball (8) falls into lowering the position
locating slot B on position locating block (7), meanwhile main control valve (5) moves right to
the lower position. The oil in the cylinder flows back into oil tank through main control valve
(5), and the implement begins to fall down. With the implement falling gradually, stop pin (2)
fixed on the stop plate of the lift shaft and the lift shaft together rotate around the lift shaft
counterclockwise, and slip along return push rod (4); after they slip to contact the lowering
position limiting stop block (3) fixed on the return push rod, they bring the return push rod
(4) move right together; at the same time turn the operation handle until position locating
steel ball (8) is pushed out of the position locating slot B. In such case, under the action of
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tension of return spring (6) of the main control valve, operation handle (10) and main control
valve (5) jump back to the neutral position at the same time. And the cylinder stops returning
oil, the implement also stops falling. Thus, the falling of the implement depends on the fixed
position of lowering return stop block (3) on return push rod (4) i.e. the closer the clearance
between lowering return stop block and operation handle is the lower the implement falls.
Loosen the tightening bolt of lowering return stop block, the return push rod will lose the
ability to make the operation handle return to neutral position. And the main control valve
stops at lowering position from beginning to end, while the cylinder is in "floating" state all
the time.
While raising the implement, push operation handle (10) to lifting position and then
position locating steel ball falls into position locating slot A (Fig.4-20), main control valve (5)
moves left to lifting position. The implement begins to rise; with the implement rising
gradually, meanwhile, return stop pin (2) rotates around the lift shaft clockwise; when the
stop pin slips to contact lifting return stop block (1), drive return push rod (4) to move left,
and at the same time rotates operation handle (10) until pull the locating steel ball (8) out of
its locating slot. In such case, under the action of the tension of return spring (6), operation
handle (10) and main control valve (5) jump to neutral position at the same time. And the oil
pump stops supplying oil to the cylinder, the implement stops rising. The raising height of the
implement depends on the fixed position of the lift return stop block (1) on the return push
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rod (4). The closer the clearance between return stop block (1) and return push rod (4) is, the
higher the implement rises.
Notes:
During operation, if the adjustment is not suitable, it possibly makes the
operation handle can not return to its position in time, and can cause parts damage due to
overload of hydraulic system.
C. Adjustment of hydraulic lifter
①
Adjustment of the utmost lifting position (Fig.4-21)
Set the control lever (1) at the neutral position which is illustrated in Fig.4-21. Rotate the
lift arm assembly (2) upward, until the clearance between the end of inner lift arm (3) and
stop pin (4) is not less than 5mm (insert a steel pad through the hole vent plug (5), control this
clearance by the pad thickness). Adjust the clearance between stop block (6) and stop pin (7)
to be 9-10mm, then fix the stop block on the return push rod (8) with bolt and nut.
②
Adjustment of the lowering position
Set the control lever (1)
at the neutral position, rotate
the
lift
arm
assembly
(2)
downwards until the desired
lowering position arrives, and
adjust
the
clearance
L
between stop block (3) and
stop pin (4) to be 9-10mm.
While in position adjusting,
adjustment should be done in
ploughing and forwarding; as the plough lowers into the soil and the required ploughing
46
depth is reached, adjust the clearance between lowering stop block (3) and stop pin (4). After
adjustment, fix stop block (3) on return push rod (5) with bolt and nut, then raise the
implement several times to check the adjustment.
If the implement is provided with a supporting wheel, the floating control needs to be
used. Meanwhile, adjust lowering stop block (3) to the position where control lever1 (1) of
distributor (valve) will not return to neutral position.
③
Adjustment of lowering speed
During adjustment, the lowering speed of the implement can be adjusted through
rotating the adjusting valve bolt (5) (see Fig.4-18). When the lowering speed is suitably
adjusted, use check screw (4) to limit the moving range of adjusting valve bolt.
④
Adjustment of safety valve
Safety valve has been adjusted before leaving the factory. In general, dismounting in
operation is not permitted anyhow. If the readjustment is necessary, it should be done on
special pressure test stand. The oil for test is HC-8(SY1152-77), the oil temperature should be
±
℃
controlled as 65
5
. When the press screw plug of safety valve is rotated clockwise, the
higher opening pressure is got, or vise versa.
In hydraulic system, as the precision of many parts is high, and the assembly parts have
been carefully tested and adjusted, cleanliness of the hydraulic oil, cleaning oil and the
environment should be especially paid attention to during operation, maintenance and fixing
the breakdowns.
Generally free dismount is not allowed.
Notes: Before starting the engine, make sure there is enough oil in the lifter housing, so
as to avoid damage to the hydraulic gear pump.
10. Use and adjustment of air brake device of trailer
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