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JWN-SERIES • RIDE-ON POWER TROWEL — PARTS AND OPERATION MANUAL — REV. #7 (03/02/07) — PAGE 30
How It Works (Figure 24)
Condition A:
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Engine Idling
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Drive Pulley: Small
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Driven Pulley: Large
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Belt: Loose and Stationary
Condition B:
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Engine Accelerating
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Drive Pulley: Small But Increasing
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Driven Pulley: Large But Decreasing
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Belt: Approaching Tightness
Condition C:
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Engine At High Speed
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Drive Pulley: Large
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Driven Pulley: Small
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Belt: Tight
The torque sensitive pulley (Figure 25) utilizes a spring and cam
bracket. Peak performance results from proper interaction between
the driven pulley spring and the ramp angle of the cam bracket.
DRIVEN PULLEY
FIXED FACE
MOVEABLE
FACE
CAM
BRACKET
SPRING
Figure 26 . Pulley Spring and Cam Bracket
JWN-SERIES— MAINTENANCE
This clutch system provides a high pulley ratio (a low gear- so to
speak) to start out and a low pulley ratio ( a high gear- so to
speak) for a high speed operation, with infinite variation between
the two.
This means that it will not be necessary to give
full throttle in
order to "break the blades/pans loose". The machine can slowly
be brought up to speed.
Clutch
Trowels equipped with optional Twin Pitch
TM
Controls may need
to have blade pitch between the two sets of blades "syncronized".
If the blades need to be syncronized this is easily accomplished
by performing the following. Refer to Figure 27.
Blade Pitch
Sometimes it may be necessary to match blade pitch between
the two sets of blades. There are some signs that this may be
necessary. For example, the differences in pitch could cause a
noticeable difference in finish quality between the two sets of
blades. Or, the difference in blade pitch could make the machine
difficult to control. This is due to the surface area in contact with
the concrete (the blade set with the greater contact area tends to
stick to the concrete more).
Matching Blade Pitch for Both Sets of Blades
1.
Lift the pitch adjustment handle on either side. Once lifted,
that side is now disconnected from the Twin Pitch
TM
system.
2.
Adjust to match the opposite side.
3.
When adjusted, lower the handle to Twin Pitch
TM
operating
position.
Figure 27. Pitch Towers
A
Twin Pitch
TM
disengaged (one side)
B
Operating Position
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