TOPIC 1. MASTS

TM 10-3930-644-14&P

MASTS, CARRIAGES AND FORKS

TOPIC 1. MASTS

A. DESCRIPTION

3. Attach a suitable chain hoist to carriage

The conversion of the hydraulic system fluid energy into

assembly.

remove chain anchor pins and

mechanical energy necessary in lift truck operation is

disconnect chains from carriage.

accomplished by the mast assembly.

4. Lower carriage out of bottom of inner mast, and

An EXTRA LIFT mast is available for all models of lift

move to the side, away from work area.

trucks, while the HIGH FREE-LIFT, TRI-LIFT, TRI

Remove chain hoist.

FREE-LIFT and TRI-MAX masts are available for certain

model trucks only.

5. With mast fully lowered, attach a sling from an

overhead crane to the mast lift-eyes to secure

The extra-lift and the high free-lift masts are basically the

entire mast assembly during removal.

same in construction with two structural uprights. The

difference between the two is the type of lift cylinder

CAUTION

used and its mounting arrangement within the mast

Be certain overhead hoist is rated to

structure. The TRI-LIFT, TRI FREE-LIFT and TRI-MAX

safely

support

mast

assembly

masts consist of a nested assembly of three (3)

weight.

structural uprights (channels) or beams.

CAUTION

All masts but the TRI-LIFT, and some of the larger

Fully retract or lower lift cylinders.

capacity TRI-MAX models, utilize two (2) lift chains for

safety and to minimize off-center loading. Due to the

6. Disconnect tilt cylinders from outer mast.

operational mechanization, all TRI-LIFT and some of the

larger capacity TRI-MAX masts, make use of four (4) lift

7. Disconnect hydraulic line(s) from lift cylinder(s).

chains. The chain anchors are individually adjustable to

ensure equal tension and a level fork carriage. The

8. Raise overhead crane high enough to relieve

chains are centrally located so as to offset any bending

pressure on the mast pivot pins. Remove pivot

action on the lift cylinder plunger(s).

pins from mast and lift truck frame; use crane to

lay mast flat on suitable supports with cylinder(s)

Should it become necessary to re-center the mast

(cluster) facing up.

channel uprights for smooth and even sliding, the

following alignment mechanics are provided (adjustment

C. TRI-MAX MAST (CLUSTER TYPE) DISASSEMBLY

method varies with the model and load capacity of mast

AND INSPECTION

employed) : a Wear plates and aligning shims. b Roller

bearings and aligning shims: c Adjusting plugs. Each of

1. Remove the lift cylinder cluster assembly and

these methods of adjustment will be discussed in detail

intermediate lift cylinder assembly (refer to TRI-

in the applicable mast service topics.

MAX CYLINDER CLUSTER REMOVAL Topic).

The removal procedure for all masts is essentially the

2. Remove the cylinder bracket from the top

same and is recommended as outlined as follows.

support on the intermediate mast section, and

disassemble and remove the channel restraint

B. REMOVAL

interlock assembly. (Refer to Figure 1.)

1. Remove the carriage forks.

3. Carefully slide the inner and the intermediate

2. Block the inner mast to give 20" to 24" clearance

mast sections out of the top of the outer mast

between bottom of mast and floor.

section, then remove the inner mast-section

from the intermediate mast section.

NOTE

Remove the capscrews and spacer

form the carriage roller supports, if

applicable.

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