Hydraulic relief valve adjustment, Hydraulic troubleshooting, Parts replacement cycles and tolerances – MBW MM121 User Manual

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8.

Reinstall inspection cover.

9.

Reinstall the engine shroud.

Hydraulic Relief Valve Adjustment

1.

Remove the engine shroud.

2.

Install a pressure gage using the side port on the left
side of the valve block (pressure port, P). The
pressure gage must read to 2,000 psi.

3.

Start engine and check that all hydraulic controls are
operating properly.

4.

With the motor in neutral, push the cylinder lever to
“dead-head” the cylinder. Allow the pressure to
stabilize. If pressure reads below 1,750 psi or above

1,850 psi, the relief valve needs adjustment. NOTE:
If pressure climbs over 1,850 psi, the engine may
stall.

5.

Loosen the jam nut on the relief cartridge located on
the left side of the valve block.

6.

Turn the set screw in to increase the pressure setting
and turn the set screw out to decrease the pressure
setting.

7.

When the pressure is set within the acceptable range,
tighten the jam nut.

8.

Stop engine and remove pressure gage from valve
block.

9.

Reinstall the engine shroud.

Hydraulic Troubleshooting

Parts Replacement Cycles and Tolerances

Problem

Test & Solution

Mixing Speed too Slow

(< 32 rpm)

1.

If speed is normal (38 - 40 rpm) in reverse, motor needs servicing.

2.

If speed is slow in both directions, but cylinder functions normally, motor needs
servicing.

3.

If speed is slow in both directions, and cylinder is slow, see “Pump Not Working”
section.

Drum Won’t Dump

1.

If motor functions are normal, cylinder needs servicing.

2.

If motor does not spin, see “Pump Not Working” section.

Pump Not Working

1.

Check engine speed. Set to 3300 rpm if necessary.

2.

Check oil temperature. If over 180 °F, see “Hydraulic Oil too Hot” section.

3.

Check relief valve and adjust if necessary.

4.

Check pump coupler and adjust or replace if needed.

5.

Remove pressure line from valve block and fill with clean oil to charge pump.
Reconnect line and check pump operation.

6.

Pump needs servicing.

Hydraulic Oil too Hot

1.

Check relief valve and adjust if necessary.

2.

Change oil according to maintenance schedule.

3.

Allow oil to cool if possible to prevent damaging hydraulic components.

Bearings

Replace anytime a bearing is rough, binding, discolored or removed from housing or
shaft.

Engine Components

Refer to your engine manufacturer’s Owner’s Manual.

Hardware

Replace any worn or damaged hardware as needed. Replacement hardware should
be grade 5 and zinc plated unless otherwise specified.

Safety Decals

Replace if they become damaged or illegible.

Seals & Gaskets

Replace if a leak is detected and at every overhaul or teardown.

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