Multiquip HTN27K_28K - Manual (Page 32)

PAGE 32 — HTN 31V
HTN-SERIES • RIDE-ON POWER TROWEL — OPERATION MANUAL — REV. #0 (06/06/07) — PAGE 32
NEUTRAL LOW SPEED HIGH SPEED
DRIVE
PULLEY
DRIVEN
PULLEY
A B C
Figure 26. Pulley Conditions
HTN-SERIES— MAINTENANCE
The "Variable Pitch Pulleys" have one fixed face , and one moveable
face . The drive pulley ( torque converter, Figure 25) 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.
Fig. 25. Variable Pitch Pulley
DRIVE
PULLEY
DRIVE
PULLEY
LOW OUTPUT
SPEED
DRIVEN PULLEY
LOW ENGINE RPM
HIGH ENGINE RPM
DRIVEN PULLEY
HIGH OUTPUT
SPEED
CENTRIFUGAL FORCE
DISTANCE
MOVEABLE
FACE
TRAVELS
MOVEABLE FACE
IS CONTROLLED
BY A SPRING
AND BELT TENSION
MOVABLE FACE IS
CONTROLLED BY
ROLLER WEIGHT ARMS
AND SPRINGS
Fig. 24. Pulley Interaction
Centrifugal force pushes the roller arms against the ramp plate,
forcing the moveable face toward fixed face squeezing the belt. (see
Figure 24 below)
WEIGHT
RAMP
PLATE
BUSHING
ROLLER ARM
SPRING
DRIVE PULLEY
Drive Pulley
The "Drive Pulley" uses centrifugal force (Figures 23 and 24)
to create a belt squeeze force transmitted at the pulley faces.
This condition functions as an automatic clutch and transmission.
CENTR
IFUGAL
FOR
CE
BEL
T
SQUEEZE
FORCE
FIXED
FACE
VARIABLE
FACE
DRIVE PULLEY
(TORQUE CONVERTER)
Figure 23. Torque Converter (Centrifugal Force)
Fig. 22 Torque Converter/Variable Pitch Pulley
The HTN-SERIES Ride-On Power Trowel 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.
The torque converter used in the HTN SERIES Ride-On Power
Trowel is a variable pitch pulley type (Figure 22) connected by a
drive belt.
Drive System Theory of Operation