Motors,

General Drive Motor Brushes Inspection

Conduct a partial inspection of the drive motor after every 1,000 hours of truck operation. If you work in an abnormally severe or caustic environment or if you have a rigorous duty cycle, inspect the motor more frequently. Set up and rigidly adhere to a strict inspection schedule to obtain the maximum efficiency from the electrical equipment. Each partial inspection of the motor should include the following:

1.Inspect the brushes for wear and for proper contact with the commutator. Record the level of wear on the brushes. This history will give you an indication of whether a brush should be changed or if it can wait until the next inspection. Refer to page 6-47 for acceptable brush length and general motor information.

NOTE: Overloading a unit is ultimately reflected in the motor and brush wear; therefore, you must take this into account when considering brush replacement.

2.Check brush spring tension. See “Drive Motor Brush Spring Tension” on page6-47.

3.Clean brushes and holders. Wipe the commutator with a dry, lint-free cloth. DO NOT USE lubricants of any kind on or around the commutator.

4.Check brush holders for solid connection to the mounting support. Tighten the mounting screws as necessary.

5.Check the cap screws holding the brush cross connectors to the brush holder body.

6.Make sure the motor terminals are secured tightly to the motor frame. Be careful not to strip the threads or crush the insulating parts.

Component Procedures

7.Check all the cap screws around the frame for tightness.

8.Keep the outside frame of the motor clean and free from dirt. Maintain a free air passage around the motor to permit heat radiation.

Replacement

If one brush needs replacement, always replace the entire set of brushes.

Use only genuine Raymond brushes. Using another type of brush could damage the commutator or cause excessive brush wear.

If the end of the brush is not already contoured to fit the commutator, use the following procedure to seat the brush to the commutator:

NOTE: If the motor commutator is not accessible, form the brush contour using a brush seating stone.

1.Move the motor brush springs out of your way.

2.Wrap a piece of 00 sandpaper around the commutator. DO NOT use emery cloth to seat brushes.

3.Move the brushes back down in their holders so that the face of the brushes matches the curve of the commutator.

4.Remove the sandpaper.

5.Blow any dust out of the motor with clean, compressed air at a maximum of 30 psi (207 kPa).

Drive Motor Brush Spring Tension Inspection

1.Turn the key switch OFF and disconnect the battery connector.

2.Remove the drive motor cover.

3.Slide the brush up slightly in its holder.

4.Insert a paper strip between the brush face and the commutator.

5.Place a small leather loop around the coil spring for the brush. If the brush spring has a loop at the brus h, hook the spring scale directly to the spring.

6.Attach a 5 lbs (2.27 kg) spring scale to the leather loop.

7.While gently pulling the scale outward, slowly pull the paper strip in the direction that the commutator normally rotates.

8.When the paper strip begins to move freely, the spring scale will read the spring brush tension.

9.Refer to the table below for proper spring tension.

10.Repeat steps 3 through 9 for the remaining brushes.

Commutator Inspection

The commutator should be inspected for surface condition and high mica. Most armatures have the mica undercut. If the armature on your motor does not, do not attempt to cut it. See Figure6-39.

The commutator must be smooth and clean to provide maximum brush wear. When commutators are not properly maintained, carbon dust can collect in the grooves between the segments. This can lead to a short circuit in the armature.

Good commutation will be indicated by a dark brown polished commutator and an evenly polished brush wearing surface.

If the commutator appear s rough, pitted, or has signs of burning or heavy arcing between the commutator bars, the motor should be removed for servicing.

Servicing

Servicing a motor for an abnormal commutator surface condition and high mica or mica undercutting requires special equipment at a motor rebuilding facility. Do not attempt to service the motor yourself.

Mica Segments