BELT-DRIVEN TRANSMISSIONS

IN THIS SECTION, YOU WILL FIND THE FOLLOWING SUBSECTIONS:

VARIABLE SPEED BELT DRIVE TRANSMISSIONS
BELT DRIVEN TRANSMISSION TROUBLESHOOTING CHART

VARIABLE SPEED BELT DRIVE TRANSMISSIONS

Variable speed belt drive vary diameters of pulleys in belt driven transmission, allowing pulleys to function as speed changers. Pulley called variator moved in and out by mechanical linkage. When variator adjusted, output speed of transmission changed, but engine speed held constant.

Variator is double grooved pulley with sliding center section. Is mounted on lever arm, and controls two belts called primary belt and secondary belt. Primary wraps around engine pulley and one groove variator. Secondary wraps around other groove variator and transmission pulley. Manually operated system levers and shafts controls movement variator. When center variator moved, tension of primary belt changed. Tension of primary changes diameter of other side variator, which changes tension of secondary belt.

When variator moved away from engine pulley, tension on primary belt increased and drive engaged. Primary belt forced closer to center of variator, which increases rotating speed of variator. At same time, secondary belt moves away from center variator. This increases working diameter that side of variator and makes transmission pulley turn faster. When variator at farthest point from engine pulley, transmission spins at maximum speed. At this point, primary belt very close to center variator, secondary rotating near outer edge variator.

Opposite adjustment when variator moved toward engine pulley, tension on primary loosened. Spring loaded secondary idler pulley pulls secondary belt deeper into groove in variator. This decreases working diameter variator on that side and slows rotation transmission pulley. If variator moved all the way in toward engine pulley, drive disengaged.

When speed in variable belt drive changed, engine must be running and belts engaged. If try to change speed when engine stopped, belts or linkage may be damaged.

BELT DRIVEN TRANSMISSION TROUBLESHOOTING CHART

A)If A Belt Wears Out Quickly
1)The sheaves may be bent, worn, or damaged
2)The sheaves may be dirty
3)The belt may have oil or grease on it
4)The operating temperature may be too high
5)The belt guide may be misaligned
6)The belt may be slipping
7)The belt may have been stored incorrectly
B)If A Belt Breaks
1)The sheaves may contain dirt or debris
2)A shock or extreme overload may have occurred
3)The belt may have been damaged during installation
C)If A Belt Turns Over In A Pulley
1)The sheaves may be misaligned
2)The sheave grooves may be worn
3)The idler sheave may be misaligned
4)The belt may be too tight
5)The belt may have been damaged during installation
D)If A Belt Is Stretched Out
1)The belt may have been too tight
2)The wrong belt may have been used
3)The belt may have been stored incorrectly
4)The belt may have been stored in a damp area
E)If A Belt Slips When Engaged
1)The belt may have oil or grease on it
2)The wrong belt may have been used
3)The control linkage may need adjustment
4)The belt may be worn or stretched
5)The machine may be overloaded
F)If Speeds Are Hard To Change
1)The linkage may need lubrication
2)The linkage may need adjustment
3)A variator sheave may be stuck or damaged
4)A variator sheave may be dirty
G)If A Belt Makes A Squeaking Noise
1)The belt tension may need adjustment
2)The belt may have been overloaded
3)The idler or sheave may need lubrication