Raymond® Walkie Pallet Truck Maintenance Manual

Component Procedures

Terminal Nuts

Whenever you disconnect and reconnect any power leads to a motor, always tighten the motor cable securing nuts with a torque wrench to prevent over-tightening them and damaging the motor. Use a second wrench on the stud terminal securing nut to avoid twisting the stud. Check these torques each time you check motor brushes.

Electric Motor Tests

Motor Types

See Figure6-41.

•A shunt-wound or separately-excited motor, such as the drive motor, has four external connections: two armature (A) and two field (E).

•A series-wound motor, such as the lift motor, has only two external connections because the armature and field windings are connected internally.

Open Circuit Motor Test

An open circuit is one in which the electrical circuit within the motor has been broken. This can be caused by:

•Bad brushes or brush springs

•A broken wire in the field or armature winding

•A loose or bad connection

Terminal Nuts PDMM-0100

Refer to Figure6-41 for the following procedure:

1.Isolate the motor from the truck circuit by removing the power cables. Use two wrenches to avoid twisting the terminal stud.

2.With the motor at room temperature, connect the leads of a digital ohmmeter between the individual circuits in the motor.

3.Observe the following measurements:

Measure all readings at room temperature.

Table 6-2: Motor Resistance Readings

4.If the meter indicates high resistance in the armature, check the condition of the brushes before replacing the motor.

5.If an open circuit is found in a serieswound motor, the motor must be disassembled by a motor rebuilding facility to isolate the problem to the field or armature circuit.

Grounded Motor Test

In a grounded motor, an electrical circuit exists between the current-carrying conductors and the motor housing. This can be caused either by direct contact or through conductive foreign material.

The ground may be caused by:

•Insulation breakdown

•Brush leads touching the motor housing

•Build-up of carbon dust or other materials

To test a motor for grounds:

Isolate the motor from the truck circuit by removing the power cables. Use two wrenches to avoid twisting the terminal studs.

Attach one lead of a digital ohmmeter to a motor terminal and the other lead to an unpainted surface of the motor housing. Set the ohmmeter to the highest scale.

If the ohmmeter reads resistance of less than 100,000 ohms, the motor is grounded. Clean, repair or replace the motor as necessary.

Short-Circuited Winding

A short-circuited winding is one in which the insulation on the field or armature has broken down at two or more points. The breakdown creates a low resistance path, allowing current to flow from one turn of the coil to another adjacent coil turn, without actually flowing through the coil wire. The result is a decrease in total resistance of the motor winding and an increase in the current flow. The severity of the short circuit depends on its location.

A shorted motor may be indicated by:

•Slow or sluggish operation

•Running faster than normal

•Overheating

•Blowing a power fuse

•Severe burning or discoloring on one or two commutator segments every 90° of rotation These symptoms can be caused by problems other than the motor itself:

•Brake too tight or dragging

•Wheel bearings too tight

•Faulty transmission

•Binding in an attached pump

Testing a motor for short-circuited windings requires special equipment at a motor rebuilding facility.

Short Circuited Armature

A short circuit in the armature will cause heating, which will probably result in burning of:

•The armature coil

•Brush wires

•Commutator segments

Visual inspection may reveal these conditions. Positive determination of a short-circuited armature requires special equipment at a motor rebuilding facility.

Drive Motor Removal

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

2.Remove the drive motor cover.

NOTE: While it is not necessary to remove the drive tire to remove the drive motor, it makes removing/installing the motor a lot easier with the tire off.

3.Disconnect the brake (deadman) switch and remove the mounting bracket from the case.

4.Remove the brake assembly. See “Brake” on page6-43.

5.Disconnect the power cables from the drive motor, noting their proper position. Use two wrenches to avoid twisting the motor stud.

6.Remove the four hex head bolts securing the motor to the drive unit.

7.Remove the motor from the drive unit.

Brush Replacement

1.Lift out the drive motor from the drive unit mounting location.

2.Remove any shields around the motor end cover to expose the brushes.

3.Lift the spring off the brush, pull the brush out of the holder.

4.Follow the brush replacement instructions. See “Drive Motor Brushes” on page6-45.

5.Replace the shields around the motor end removed in step 2.

Motor Disassembly

1.Remove the pinion gear lock nut and pinion gear from the motor armature shaft.

2.Remove and discard the old O-ring.

3.Remove the four screws holding the brush end bell to the field housing.

4.Separate the end bell from the field housing. The armature will come out with the end bell.

Component Procedures

Drive Motor

5.To remove the end bell from the armature, remove the snap ring that holds the bearing in the end bell. If needed, press off the bearing and replace.

Installation

1.Thoroughly clean all parts with solvent or other non-corrosive cleaning fluid. Air dry all parts. The O-ring on the drive end of motor should be replaced at this time with a new O-ring.

NOTE: Install the drive motor in a dirt-free area.

2.Install the brake assembly by lifting one brake shoe at a time and attach with two (2) hex head cap screws. Apply thread-locking compound (P/N 990-536) and torque to 25 to 30 ft lbs (35 to 42 Nm).

3.Position the brake actuating lever. See “Brake Shoe Adjustment” on page6-43.

4.Install the brake drum and the lock nut.

5.Install the pinion gear and the lock nut on the armature shaft. Place a wrench on both lock nuts and torque to 75 ft lbs (105 Nm).

6.Install a new O-ring on the motor drive end.

NOTE: Always make sure that the O-ring has been lubricated with petroleum jelly before reinstalling.

NOTE: When reinstalling the drive motor the power cables must be kept to the back side of the gear housing or the motor will not go into the gear case.

7.Slide the drive motor in the gear case and work it around until the motor lines up with the cluster gear.

8.Install the four hex head cap screws and torque to 35 ft lbs (49 Nm).

9.Attach the power cables with four hex head bolts. Torque to 60 to 84 in. lbs (6.8 to 9.5 Nm). Use a second wrench on the stud terminal securing nut to avoid twisting the motor stud. See “Terminal Nuts” on page6-49.

10.Reattach the brake (deadman) switch and wires as described on page 6-27.