Placement of Telescoping Gage (M977 and M985 only).

TB 9-2320-279-34

2-8.3. Placement of Telescoping Gage (M977 and M985 only).

NOTE

To obtain a true reading of bearing vertical movement, the telescoping gage must

be positioned correctly.

a. Ensure that the gage is straight up and down in all directions, front to back and side to

side. It is not necessary to measure this, but try to get it as close as possible with a

visual inspection from different angles.

b. The telescoping gage must be in line with the axial centerline of the boom for all

measurements.

c. To ensure a consistent reading, the telescoping gage must be as close as possible to

the outside diameter of the swing gear tooth tip, as the allowable bearing movement

only applies at the tip of the gear tooth. The gage reading will be magnified if the

contact point is off of the outer diameter of the swing gear tooth tip.

d. Always verify that the reading is correct by measuring at least twice.

2-8.4. Turntable Bearing Inspection Procedures.

________

WARNING

When performing these inspection procedures, do not position yourself

underneath the boom when the crane controls are being operated. Failure to

comply could result in severe injury or death to personnel.

Tools Required (or equivalent)

1. Dial indicator with at least one inch of plunger travel with .001 inch graduations.

2. Magnetic base for dial indicator.

3. Carpenters level.

4. Telescoping gage (M977 and M985 only).

5. Micrometer (M977 and M985 only).

6. Magnetic protractor.

NOTE

Any reading equal to or over .065 inch (1.65 mm) will require a new bearing to be

ordered and installed as soon as possible. If that reading occurs on the first step

of the inspection, it is not necessary to continue the inspection. However, even if

the first reading is within the specifications, it is still necessary to complete all of

the remaining steps in the inspection procedure.

For measurements with the boom nose positioned over rear and front of M977,

M984A1, and M985, perform steps b. through g.

For measurements with the boom nose positioned over driver and passenger

side of M984A1, perform steps b. through g.

For measurements with the boom nose positioned over driver and passenger

side of M977 and M985, perform steps i. through n.

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