Stow STR36SP manual Drive System Theory of Operation

Drive System Theory of Operation

The STR36SP-SERIES Ride-On PowerTrowel is equipped with a "Torque Converter" which supplies torque to both the left and right gearboxes.

The function of the torque converter is to automatically deliver the correct amount of torque required by the trowel under all load conditions.This enables the trowel to deliver the necessary torque for float pan applications and the high rotor speeds required for burnishing concrete.

ThetorqueconverterusedintheSTR36SPSERIESRide-OnPower Trowel is a variable pitch pulley type (Figure 21) connected by a drive belt.

Fig. 21. Torque Converter/Variable Pitch Pulley

Drive Pulley

The "Drive Pulley" uses centrifugal force (Figures 22 and 23) to create a belt squeeze force transmitted at the pulley faces. This condition functions as an automatic clutch and transmission.

		TRI
	N		FU	G
E
C				A	L
					F
					O
					R
					C
					E

FIXED

FACE

VARIABLE

FACE

	SQUEEZE
BELT	FORCE	DRIVE PULLEY
		(TORQUE CONVERTER)

Figure 22. Torque Converter (Centrifugal Force)

STR36SP-SERIES— MAINTENANCE

Centrifugal force pushes the roller arms against the ramp plate, forcing the moveable face toward fixed face squeezing the belt. (see Figure 23 below)

CENTRIFUGAL FORCE

DISTANCE	DRIVE	LOW OUTPUT
			SPEED	MOVEABLE FACE
	PULLEY
MOVEABLE
				IS CONTROLLED
FACE
				BY A SPRING
TRAVELS
				AND BELT TENSION
	LOW ENGINE RPM
		DRIVEN PULLEY
MOVABLE FACE IS			HIGH OUTPUT
CONTROLLED BY
		DRIVE		SPEED
ROLLER WEIGHT ARMS
		PULLEY

AND SPRINGS

HIGH ENGINE RPM

DRIVEN PULLEY

Fig. 23. Pulley Interaction

The"VariablePitchPulleys"haveonefixedface,andonemoveable face.The drive pulley ( torque converter, Figure 24) moveable face is controlled by roller weight arms and springs, which change position according to engine speed.The driven pulley moveable face is controlled by a spring and belt tension.

DRIVE PULLEY

RAMP

PLATE

BUSHING

SPRING

ROLLER ARM

WEIGHT

Fig. 24. Variable Pitch Pulley

A	B	C	DRIVE
			PULLEY

DRIVEN

PULLEY

NEUTRAL LOW SPEED HIGH SPEED

Figure 25. Pulley Conditions

STR36SP-SERIES • RIDE-ON POWER TROWEL — OPERATION AND PARTS MANUAL — REV. #1 (09/16/11) — PAGE 30