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Electric Clutch
An electric clutch is used to engage the coring head on
the ProCore 648. The electric clutch is mounted on the
engine crankshaft and engages when current is applied
to the clutch. The clutch also incorporates a magnetic
brake to stop clutch rotation when the clutch is de–ener-
gized.
When the ”OK to lower” latching circuit is closed and the
coring head is lowered enough to close the aeration #3
proximity switch, the clutch relay will be energized. This
energized relay provides a current path to energize and
engage the clutch. See Electric Clutch Circuit in the Cir-
cuit Operation section of this chapter for additional elec-
tric clutch information.
Testing
1. Park machine on a level surface, fully raise coring
head, engage parking brake, stop engine and remove
key from the ignition switch. Secure coring head with
service latch.
1. Remove pump belt cover from machine (see Opera-
tor’s Manual).
2. Remove exhaust system shield (see Exhaust Sys-
tem Removal in the Service and Repairs section of
Chapter 3 – Kohler Engine).
3. Locate electric clutch on engine crankshaft (Fig. 35).
Unplug machine wire harness connector from clutch.
4. For accurate resistance measuring, clutch should be
at approximately 68
o
F (20
o
C) when coil resistance is
measured.
NOTE: Prior to taking small resistance readings with a
digital multimeter, short the meter test leads together.
The meter will display a small resistance value (usually
0.5 ohms or less). This resistance is due to the internal
resistance of the meter and test leads. Subtract this val-
ue from from the measured value of the component you
are testing.
5. Using a multimeter (ohms setting), verify clutch coil
resistance between the two terminals of the clutch wire
connector. Coil resistance should be 1.75 to 1.93 ohms.
6. If coil resistance is incorrect, replace clutch.
7. Measure gap between clutch rotor and armature
(Fig. 36). Gap should be less than .125” (3.18 mm). This
gap is not adjustable and increases as clutch compo-
nents wear. If gap exceeds .125” (3.18 mm), replace
clutch.
8. As an additional test, apply 12 volts to the terminals
of the clutch. The clutch should engage. If clutch does
not engage when voltage is applied, replace clutch.
9. If clutch removal is necessary, see Electric Clutch in
the Service and Repairs section of this chapter.
10.Install exhaust system shield (see Exhaust System
Installation in the Service and Repairs section of Chap-
ter 3 – Kohler Engine).
11. Install pump belt cover to machine (see Operator’s
Manual).
1
Figure 35
1. Electric clutch
1
2
Figure 36
1. Electric clutch
2. Feeler gauge
Electrical System
Page 5 – 26
ProCore 648