Lull 944E-42 Service Manual User Manual download pdf (Page 393)

100

101

8.141

Model 644E-42/944E-42 Rev. 6/04

Hydraulic System

Not

Check the flow at the end of the circuit

at the female coupler.

Repair/replace pump

NOTE:

When checking pressures in

circuits, refer to Section 8.7,

“Hydraulic System Testing,” for

correct pressure readings.

NOTE:

Before pressure checking

circuits, refer to Section 9.8.29,

“Dual Joystick - Auxiliary

Hydraulic Circuit &

Troubleshooting,” to ensure the

electrical circuits for the pilot

select valve are functioning

Not

Check port relief at main control valve

Replace the relief valve on

auxiliary hydraulic section of

main control valve.

There are no auxiliary hydraulic

functions.

Not

Check the standby pump pressure at

implement pump pressure tap.

If OK

Replace unloader cartridge

on main control valve.

Not

Check pilot pressure at “PPG” port of

accumulator charge/secondary

function valve.

Adjust/repair/replace

pressure reducing cartridge

on accumulator charge/

secondary function valve.

Not

Inspect pump. Refer to

Hydraulic Testing

pages 8.12 through 8.54.

Check the cycle times for boom LIFT

and boom EXTEND to determine

pump performance. Pump flow

directly controls these cycle times.

Refer to Section 2.5.6, “Hydraulic

Cylinder Performance Specifications,”

for correct cycle times.

If OK

Not

Adjust/replace main relief

cartridge on main control

valve.

If OK

Not

Repair/replace joystick.

Check the main relief pump pressure

at implement pump pressure tap.

Refer to Section 8.7, “Hydraulic

System Testing,” test sequence 7.

Install pressure gauge in the pilot

supply line, between the joystick &

pilot select valve and pilot select valve

&auxiliary hydraulic section of main

control valve. Check pilot pressure.

With the button pressed and joystick

moved all the way to the right the

pressure should be 444 ±22 psi

(30,6 ±1,5 bar).

Before troubleshooting any

hydraulic circuit, ALWAYS

begin by checking the

following:

1. Hydraulic oil level in the

reservoir

2. All hoses, tubes, fittings

for leaks, kinks,

interference, etc.

3. Air in the lines

1 2 ... 388 389 390 391 392 393 394 395 396 397 398 ... 845 846

Comments to this Manuals

No comments

Lull 944E-42 Service Manual User Manual Page 393

Comments to this Manuals

Related products and manuals for Special machinery Lull 944E-42 Service Manual