Loader Bobcat 853, 853H. Instruction - page 17

HYDRAULIC CYLINDERS (Cont’d)

Assembly

Use the following tools to assembly the cylinder:

MEL1396 – Seal Installation Tool
MEL1033 – Rod Seal Installation Tool
Piston Ring Compressor
Spanner Wrench

Wash the cylinder parts in solvent and air dry them.

Inspect the cylinder parts for nicks, scratches or other
damage. Replace any damaged parts.

Always install new O–rings and seals during assembly.

Lubricate all O–rings and seals with hydraulic oil during
installation.

Install the new seal on the tool and slowly stretch it until
it fits the piston [A].

Allow the seal to stretch for 30 seconds before installing
it on the piston.

Standard Piston: Install the seal (Item 1) [B] and O–ring
(Item 2) [B] on the piston (Item 3) [B].

Cushion Piston: Install the seal and O–ring on the piston
(Item 1) [C].

Use a ring compressor to compress the seal to the correct
size. Leave the piston in the compressor for about three
minutes.

Install the rod seal on the rod seal tool [D].

Rotate the handles to collapse the rod seal [D].

NOTE: During installation the O–ring side of the seal

must be toward the inside of the cylinder.

A

P–07424

C

P–07438

1

D

P–07427

853, 853H Loader

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Service Manual

B

P–07430

3

2

1

HYDRAULIC CYLINDERS (Cont’d)

Assembly (Cont’d)

Install the rod seal in the head [A].

Install the wiper seal with the wiper toward the outside of
the head.

Install the thin O–ring (Item 1) [B].

Install the back–up washer (Item 2) [B] and thick O–ring
(Item 3) [B] into the groove on the head.

Tilt Cylinder: Install the head (Item 1) [C], and the piston
(Item 2) [C]. The small diameter of the piston goes into the
cylinder tube first.

Tilt Cylinder: Grease the piston where the nut contacts the
piston. Do not get grease on the threads.

Tilt Cylinder: Install the nut (Item 3) [C].

Tilt Cylinder: Tighten the nut to 100 ft.–lbs. (136 Nm)
torque.

Tilt Cylinder: Mark the end of the shaft and nut [D].
Tighten the nut an additional 135 degrees or 2–1/4 flats
[D].

NOTE: Clean and dry the threads before install the

nut. Install the new nut from the kit.

A

P–07425

C

P–07434

1

2

3

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853, 853H Loader

Service Manual

B

P–07422

1

2

3

D

P–10456

P–10450

HYDRAULIC CYLINDERS (Cont’d)

Assembly (Cont’d)

Lift Cylinder: Install the head (Item 1) [A], and spacer
(Item 2) [A].

Lift Cylinder: Install the piston (Item 3) [A], and the nut
(Item 4) [A].

Lift Cylinder: Tighten the nut (Item 4) [A] to 600 ft.–lbs.
(814 Nm) torque.

Put the base end of the hydraulic cylinder in a vise.

Tighten the head using a spanner wrench [B] & [C].

NOTE: Clean and dry the threads before install the

nut. Install the new nut from the kit.

B

P–07429

A

P–07428

1

2

4

3

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C

P–07435

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.

MAIN RELIEF VALVE

Checking The Main Relief Valve

The tools listed will be needed to do the following
procedure:

MEL10003 – Hydraulic Tester
MEL10006 – Hydraulic Test Kit

Turn the key switch to the OFF position, as the engine
stops running, turn the key switch all the way to the left to
release the hydraulic pressure at the front auxiliary quick
couplers.

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

Connect the IN port of the hydraulic tester to the female
quick coupler on the loader [A].

Connect the OUT port of the hydraulic tester to the male
quick coupler on the loader [A].

The hydraulic tester must be in the fully open
position before you start the engine.

I–2024–0284

Put jackstands under the front axles and rear
corners of the frame before running the engine
for service. Failure to use jackstands can allow
the machine to fall or move and cause injury or
death.

W–2017–0286

Start the engine and run at low engine idle RPM. Push the
mode switch (Item 1) [B] two times (on the instrument
panel) to engage the front auxiliary hydraulics, the light
(Item 2) [B] will come ON.

Push the button (Item 1) [C] for fluid pressure to the quick
couplers.

Watch the flow meter on the hydraulic tester to make sure
the flow is correct. Increase the engine speed to full RPM.

There should be 18.0 GPM (68 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
2700–2750 PSI (18617–18961 kPa).

If the relief pressure is not correct, stop the engine.
Replace or adjust the main relief valve. (See Page 2–15.)

A

P–05061

C

P–00387

Right

Steering

Lever

Control

1

P–00391

Left

Steering

Lever

Control

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853, 853H Loader

Service Manual

B

B–13443

1

2

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