Backup Hydraulic System Components

Introduction, Maintenance, And Troubleshooting of the Primary/Backup Hydraulic System
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Accomplish this by positioning the internal spool, which

determines the direction of rotation.

The valves may be

electrically operated by the control switches or manually

operated by pressing the buttons on either side.

o Temperature Gage - displays the temperature of the hydraulic

fluid in the reservoir, as monitored by the temperature

The temperature of the hydraulic fluid in the

reservoir should not exceed 160F.

o Level Gage - displays the level of the hydraulic fluid in the

reservoir, as monitored by the fluid level transmitter. The gage

is graduated from empty (E) to full (F) in 1/4 tank increments.

The fluid level in the reservoir should not measure less than

3/4.

Backup Hydraulic System Components.

Use the following components, shown in Figure 3F, to engage the backup

hydraulic system:

o Manual Hydraulic Pump - when manually activated, provides the 125

to 150 psi to engage the backup hydraulic pump clutch system to

the main engine. Measure the pressure generated by this pump by

a gage attached to it.

o Backup Hydraulic Circuit Dump Valve - when opened, permits the

backup hydraulic pump to disengage from the main engine. For the

backup pump and hydraulic circuits to function, you must close

this valve.

o Selector Valve - determines which hydraulic pump circuit is to be

activated.

When you push the valve handle in, you select the

primary hydraulic pump circuit. When you pull the handle out,

you select the backup hydraulic pump circuit. For the hydraulic

system to function, the selected hydraulic pump must also

function.

Backup operation capabilities are provided for many of the M992 systems;

the hydraulic system is one of them. The next part of this subcourse

describes how to operate the hydraulic system in the event of a hydraulic

or electrical power loss.

OD1703

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