Rockwell Commander 112 - SECTION III HYDRAULICS; GENERAL DESCRIPTION

Rockwell Commander 112

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ROCKWELL

COMMANDER

112/B/TC/TCA

MAINTENANCE

MANUAL

SECTION III

HYDRAULICS

SECTION

III

HYDRAULICS

T

ABLE

OF

CONTENTS

Page

GENERAL DESCRIPTION . . . . . . . . . . . . . . . . .

..

3-

1

GENERAL MAINTENANCE

PRACTICES

.•...

3-

2

Functional

Test

Procedure

...............

3

..

6

HYDRAULIC SYSTEM COMPONENTS

........

3-

6

Actuating

Cylinders

.....................

3-

6

GENERAL

DESCRIPTION

MODEL 112

(Serial

numbers

thru

380).

The

hydraulic

power

supply

is

an

integrated

unit

containing

a

rever-

sible

electric

motor-driven

hydraulic

pump,

fluid

reservoir,

pressure

control

valves,

thermal

relief

valves,

and

a

gear

up

check

valve.

The

hydraulic

power

pack

is

located

in

the

left

forward

area

of

the

aft

fuselage

section.

A

landing

gear

selector

switch,

mounted

on

the

instrument

panel,

electrically

actuates

the

hydraulic

pump

in

the

power

pack,

to

control

di-

rection

of fluid flow to

permit

landing

gear

extension

or

retraction.

When

the

landing

gear

selector

switch

is

pulled

out

to

clear

a

detent,

and

placed

in

the

UP

pOSition,

the

hydraulic

pump

is

energized

and

hydraulic

fluid

is

directed

to

the

up

port

of

each

gear

actuating

cylinder

to

retract

the

gear.

Fluid

on

the

opposite

side

of

each

actuating

cylinder

is

returned

to

the

power

pack

fluid

reservoir.

When

all

three

gears

are

retracted,

a

hydraulic

actuating

switch

located

adjacent

to

each

actuating

cylinder,

de-energizes

the

hydraulic

pump.

Any

loss

of

hydraulic

pressure

which

allows

any

gear

to

partially

extend

is

sensed

by

the

respective

gear

uplock

position

switch,

and

the

hydraulic

pump

is

en-

ergized

and

the

gear

retracted.

When

the

gear

selec-

tor

switch

is

placed

in

the

DOWN

pOsition,

the

hydrau-

lic

pump

is

energized

and

hydraulic

fluid

is

directed

to

the

down

port

of

each

actuating

cylinder

to

extend

the

gear.

When

all

three

gears

are

extended

and

locked,

piston

locks

on

each

actuating

cylinder

engage,

and

the

hydraulic

actuating

switches

de-energize

the

hydraulic

pump.

The

gears

are

held

down

and locked

by

the

piston

locks

on

each

actuating

cylinder,

and

the

overtravel

in

the

drag

brace

assisted

by

emergency

extension

springs.

The

system

is

protected

from

Change 2

Page

Hydraulic

Power

Pack

...................

3-

9

Emergency

Extension

Valve

..............

3-11

Miscellaneous

Hydraulic

Components

......

3-11

TROUBLE SHOOTING

......................

3-12

excessive

pressure

by

the

thermal

relief

valve

which

opens

to

relieve

pressure

at

2025

to

2425

pSi.

Emer-

•

gency

gear

extension

is

accomplished

by

manually

actuating

the

emergency

extension

valve,

located

on

the

left

side

of

the

console.

When

actuated,

this

valve

bypasses

fluid

from

the

up

Side

of

each

gear

actuating

cylinder

to

the

power

pack

fluid

reservoir.

The

gears

then

drop

by

gravity,

assisted

by

the

emergency

ex-

tension

springs.

When down

and locked

over

center

three

green

lights

are

illuminated

when

all

three

downlock

position

switches

and

the

three

hydraulic

actuating

switches

indicate

a

gear

safe

condition

(see

Section

VI

for

Adjustment).

With

the

emergency

ex-

tension

valve

in

the

down pOSition

the

gear

will

not

retract

because

the

pressure

is

being

relieved

through

the

extension

valve

back

to

the

reservoir

and

not

to

the

actuating

cylinders.

Other

hydraulic

components

using

MIL-H-5606

hydraulic

fluid

held

within

self

contained

reservoirs

are

installed

in

the

airc

raft

and

are

not

functionally

associated

with

the

main

hydraulic

system.

These

components

are

master

brake

cylinders,

nose

shimmy

dampener,

nose

and

main

gear

struts

and

wheel

brakes.

(see

Figure

3-1

and

3-2).

MODEL 112

(Serial

numbers

381

and

subsequent).

MODELS

112B/TC/TCA.

The

hydrauliC

actuating

switches

have

been

replaced

by

hydraulic

pressure

switches

located

in

the

forward

fuselage

section

under

the

floor

in

the

area

of

the

left

rear

seat.

These

switches

sense

hydraulic

pressure

and

cycle

the

hy-

draulic

pump

to

maintain

system

pressure

with the

gear

in

the

up

or

down

position

as

applicable.

Refer

to

Figure

3-3

for

aircraft

effectivity

of

the

power

pack,

gear

pressure

switches,

and

pressure

settings

of

these

components.

3-1

Copyright Commander Owners Group 2013 All Rights Reserved

**unofficial copy**

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