Loader Bobcat 853, 853H. Manual - part 19

W–2006–0284

When the engine is running during service, the
steering levers must be in neutral and the
parking brake engaged. Failure to do so can
cause injury or death.

DUAL PRESSURE MAIN RELIEF VALVE (S/N
512811001 & Above) W/Select Valve (JEM) (Cont’d)

Checking The High Setting (Cont’d)

Install the hose (Item 1) [A] on the secondary auxiliary
quick couplers as shown.

NOTE: The High Horsepower switch should be in the

OFF position.

Push the button (Item 1) [C] to engage the detent position
to the front auxiliary quick couplers.

Push and hold the button (Item 2) [C] for fluid flow through
the secondary auxiliary couplers and hose loop.

Watch the flow meter on the hydraulic tester to be sure the
flow is correct.

There should be approximately 18.0 GPM (68,1 L/min.)
free flow. Turn the restrictor control on the tester, until the
main relief valve opens. The correct pressure for the main
relief is 3000 PSI (20685 kPa).

Release the button (Item 2) [C] and push the button (Item
1)  [C] to disengage the detent position to the front
auxiliary quick couplers.

If the relief pressure is not correct, stop the engine.
Replace or adjust the main relief valve. (See Page 2–27.)

NOTE: The hose loop (Item 1) [A] (with .070 inch

orifice), provides restriction and pilot
pressure necessary to shift the dual stage
main relief valve to the high pressure setting.

Start the engine and run at low idle RPM. Increase the
engine speed to full RPM. Push the mode switch (Item 1)
[B] twice (on the instrument panel) to engage the front
auxiliary hydraulics detent, the lights (Items 2 & 3) [B] will
come ON.

A

P–05196

1

C

P–00389

P–00391

Left

Steering

Lever

Right

Steering

Lever

Control

Control

1

2

853, 853H Loader

–2–25–

Service Manual

B

P–00998

2

1

3

DUAL PRESSURE MAIN RELIEF VALVE (S/N
512811001 & Above) W/Select Valve (JEM) (Cont’d)

Adjusting The Low Setting

NOTE: Adjust the low pressure setting before

adjusting the high pressure setting.

Correct pressure for the low setting is 2700–2750 PSI
(18617–18961 kPa). (See Page 2–23 for the correct
procedure to check the setting.)

To adjust the low pressure setting on the main relief valve,
(Item 1) [A] disconnect the pilot hose (Item 2) [A] from the
adapter fitting (Item 3) [A].

Remove the adapter fitting (Item 3) [A].

Remove the high pressure adjustment housing (Item 1)
[B] from the main relief valve.

Use a 1/4’’ allen wrench (Item 1) [C] to turn the adjusting
screw (Item 2) [C] in to increase pressure or out to
decrease pressure.

One turn is equal to approximately 490 PSI (3379 kPa).

Reinstall the high pressure adjustment housing and
adapter.

Reconnect the pilot hose.

Start the engine and increase the engine speed to full
RPM. Check for the correct pressure setting.

Repeat the procedure until the pressure setting is
approximately 2700–2750 PSI (18617–18961 kPa).

When the correct pressure setting is reached, the next
step is to set the high pressure adjustment on the main
relief valve. (See Page 2–24 for the correct procedure.)

Stop the engine.

A

E–02232

2

1

3

Select Valve
(JEM Block)

Control Valve

C

MC–01654

1

2

B

MC–01654

1

–2–26–

853, 853H BICS Loader

Service Manual

DUAL PRESSURE MAIN RELIEF VALVE (S/N
512811001 & Above) W/Select Valve (JEM) (Cont’d)

Adjusting The High Setting

NOTE: Adjust the low pressure setting before

adjusting the high pressure setting.

Correct pressure for the high setting is 3000 PSI (20685
kPa). (See Page 2–24 for the correct procedure to check
the setting.)

To adjust the high pressure setting on the main relief valve
(Item 1) [A] disconnect the pilot hose (Item 2) [A] from the
adapter fitting (Item 3) [A].

Remove the adapter fitting (Item 3) [A].

Use a 1/4’’ allen wrench (Item 1) [B] to press the push pin
(Item 2) [B] in until it bottoms out.

Turn the adjusting guide (Item 3) [B] in to increase
pressure or out to decrease pressure.

One turn is equal to approximately 390 PSI (2689 kPa).

Reinstall the adapter fitting and pilot hose.

Check for the high pressure setting.

Reconfirm the correct adjustment.

Repeat the adjustment procedure if necessary.

A

E–02232

2

1

3

Select Valve
(JEM Block)

Control Valve

B

MC–01654

3

2

1

853, 853H BICS Loader

–2–27–

Service Manual

HYDRAULIC CONTROL VALVE

Removal And Installation (Cont’d)

Stop the engine. Move the hydraulic controls to release
the hydraulic pressure. Raise the seat bar.

Lift and block the loader. (See Page 1–1.)

Raise the operator cab. (See Page 1–1.)

Clean the area around the control valve.

Remove both cotter pins from the clevis pins connecting
the linkages to the valve spools [A].

Remove the clevis pins (Item 1) [A] from the linkages.

Remove the two tubelines (Item 1) [B] from the auxiliary
section of the control valve.

Disconnect the front auxiliary control valve return hose
(Item 2) [B].

Remove the two tubelines (Item 1) [C] from the tilt section
on the control valve.

Remove the three tubelines (Item 1) [D] from the lift
section on the control valve.

Never work on a machine with the lift arms up
unless the lift arms are secured by an approved
lift arm support device. Failure to use an
approved lift arm support device can allow the
lift arms or attachment to fall and cause injury
or death.

W–2059–0598

A

CD–10937

1

C

CD–10939

1

D

CD–10940

1

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853, 853H BICS Loader

Service Manual

B

CD–10938

1

2