Clutch, Electric (Pto); Troubleshooting - Toro 315-8 User Manual

Clutch, Electric (PTO)

Purpose
This clutch electrically controls the engagement and
disengagement of the Power Take Off (PTO) pulley.
How It Works
The PTO clutch is composed of three major
components; the field, the clutch plate, and the friction
plate. The clutch plate always turns with the engine.
The field is a coil of wire on an iron core, which
becomes an electromagnet when power is applied.
The friction plate can slide up and down on the
crankshaft axis. It is normally spring loaded so that it is
not in contact with the clutch plate and is pressed
against the brake material opposite the clutch. When
power is applied, the friction plate is drawn toward the
clutch plate and the two rotate as one.
Testing
If the electric PTO clutch is not engaging or is
suspected as a cause of electrical problems, use the
troubleshooting steps. These procedures will help you
determine if the clutch has failed or is the cause of the
electrical problem.
Coil Resistance Measurement
1. Disengage the PTO, set the parking brake, turn
the ignition key to OFF and remove the key.
2. Disconnect clutch wire connector.
3. Set the multimeter or volt/ohm meter to check
resistance (ohms).
Demystification Glossary
4. Connect the meter lead wires to the wires in the
clutch connector (Figure 1).
Figure 1
5. The meter should read between 2.40 ohms and
3.40 ohms. If the reading is above or below these
readings, the field has failed and needs to be
replaced. If the reading is between these two
limits, measure the clutch current draw.
Measuring Clutch Current Draw
1. Disengage the PTO, set the parking brake, and
turn the ignition to OFF.
2. Disconnect the clutch wire connector.
3. Set the multimeter to check amps (10 amp scale).
4. Connect the positive meter lead to the tractor
terminal (1) of the clutch wire, Figure 2.
5. Connect the negative meter lead to the
corresponding wire terminal (3), Figure 2.
6. Connect a short jumper lead from terminal (2) to
(4), Figure 2.
7. Turn the ignition switch to the "RUN" position and
the PTO switch to the "ON" position.
GLOSSARY
3-6
3 - 3