Service Manual

Multi Pro 1200/1250Page 7 – 4Drive Train

Drive Clutch

1. Fixed sheave

2. Moveable sheave

3. Spider assembly

4. Cover

5. Washer

6. Plastic cap

7. Spring

8. Cam weight

9. Roller

Figure 4

Principles of Operation (Fig. 4)

The operation of the drive clutch is affected by engine

shaft speed. With the engine not turning, the drive belt

rests low within the drive clutch sheaves as the pressure

of the spring holds the sheaves apart. As the engine in-

creases in speed, the cams attached to the moveable

sheave move outward as they spin about the engine dri-

veshaft. The outward movement of the cams presses

against the rollers and overcomes spring pressure

through the spider assembly, which forces the move-

able sheave closer to the fixed sheave. This inward

movement of the sheave engages the drive belt to drive

the driven clutch.

With increasing engine speed, the moveable sheave

continues to move inward, which forces the drive belt to

ride towards the outer diameter of the clutch sheaves.

When engine speed is decreased, the cams exert less

force on the rollers and thus the spring. The spring pres-

sure overcomes the force of the cams, and shifts the

moveable sheave away from the fixed sheave. The

drive belt disengages from the clutch sheaves at a point

where the force of the spring is greater than that of the

weights.