Manitowoc 1400A User Manual

National Crane 1-21-2019 Control # 104-07 2-9
1400A SERVICE MANUAL HYDRAULIC SYSTEM
2
PRESSURE SETTING PROCEDURES
Description
The valves in the hydraulic system must be properly
adjusted to protect a component, circuit, or system from over
pressurization (relief valves) and ensure the components
receive the appropriate pressure and flow.
Maintenance
Relief valves are checked and adjusted by causing a given
circuit to reach its prescribed pressure limit (stall). At this
point the relief valve opens, returning hydraulic oil to the
reservoir. Hydraulic motor circuits can be stalled by
preventing rotation of the motor shaft prior to actuating the
control valve. Cylinder circuits can be stalled by extending or
retracting a cylinder to its limit of travel.
Correct relief valve adjustment is mandatory for proper
functioning of a hydraulic circuit. Only qualified technicians
using the correct equipment should make pressure
adjustments when pressure adjustments are needed.
NOTE: Use an accurate 0 to 5,000 psi (0 to 34,500 kPa)
pressure gauge when adjusting relief valves. To
adjust a relief valve, turn the adjustment screw (in
to increase or out to decrease) until the proper
setting is reached.
Release the control lever after taking each reading
and while making adjustments. When the proper
pressure setting has been attained, tighten the
adjustment screw locknut and recheck the
pressure.
It is only necessary to hold hydraulic pressure long
enough (usually a few seconds) to gain an
accurate reading. Do not overload the hydraulic
circuits for long periods of time.
Reservoir oil temperature is to be 60° to 71° C
(140° to 160° F).
Preparation
• Run the engine until the hydraulic oil temperature
reaches a minimum of 60° to 71° C (140° to 160° F).
• Shut down the engine.
FIGURE 2-2
Telescope Out Relief
Telescope In Relief
Boom Up Relief
Boom Down Relief
System Relief
Load Sense Relief
Main Control Valve
with Optional Aux
Hoist Section
CAUTION
Do not overtighten the adjustment screw or locknut.
Do not hold the relief valve open for more than one minute
at a time.
DANGER
Do not attempt to loosen the fittings in pressurized lines or
while the hydraulic pumps are in operation or personnel
injury could result.
!
Fo
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Reference
Only

Manitowoc 1400A Specifications

General

Brand	Manitowoc
Model	1400A
Category	Construction Equipment
Language	English