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BALANCE OF SPRING FORCE CALCULATION
(below numbers are example only)
IT IS REQUIRED THAT THE MINIMUM DETENT SPRING TORQUE IN PARK POSITION
BE GREATER THAN THE MAXIMUM ACTUATOR TORQUE IN TOOTH-BUTT CONDITION
T MIN DETENT SPRING T MAX ACTUATOR SPRING
DETENT SPRING........(DETAILED DRAWING INFO)
DETENT LEVER..........(DETAILED DRAWING INFO)
CALCULATION OF MAXIMUM MANUAL SHAFT TORQUE DUE TO ACTUATOR SPRING:
(below numbers are example)
ACTUATOR SPRING....... (DETAILED DRAWING INFO)
FREE HEIGHT = 66.13 mm
FORCE (MIN) = 28N @ 45mm
FORCE (MAX) = 32N @ 45mm
SOLVE FOR K :
SPRING RATE (MIN) = 28N / (66.13mm - 45mm) = 1.32N/mm
SPRING RATE (MAX) = 32N / (66.13mm - 45mm) = 1.51N/mm
SOLVE FOR X :
SPRING HEIGHT MIN AT PARK TOOTH-BUTT CONDITION:
45mm - 12.2mm (MAX ACTUATOR SPRING COMPRESSION) = 32.8mm
SPRING FORCE AT TOOTH-BUTT CONDITION (MAX)
F MAX = K MAX* X MAX COMPRESSION
F MAX ACTUATOR SPRING : 1.51/mm * (66.13mm - 32.8mm) = 50.3 (7)
CALCULATION OF MINIMUM MANUAL SHAFT TORQUE DUE TO DETENT SPRING:
(below numbers are example)
DETENT SPRING FORCE IN PARK POSITION (DETAILED DRAWING INFO) = 26.0 +3N -3N (tol)
AT AN INSTALLED HEIGHT OF 7.O MM (basic non-tol) (4)
GIVEN DELTA X :
MAX DIST ROLLER CENTERLINE TO CASE AT PARK POSITION = 7.5
SOLVE FOR K :
K = F/X (WHERE X IS FREE HEIGHT FROM DETAILED DRAWING)
K NOM = 26.0N / 18.6 = 1.4N/mm
K MIN = 26.0N / 18.6 = 1.2N/mm
K MAX = 26.0N / 18.6 = 1.6N/mm
THEREFORE FMIN :
FMIN = FMINPARK - KMIN
FMIN 23.0N + 1.2N/mm * (7.0mm -7.5mm) = 22.4N (22.4N is a force to manual shaft pivot point
when in park position)
(1)
(1)
(2)
(2)
(3)
(3)
(4)
(5)
(5)
DETENT SPRING / TORQUE..............47.4 * 34.8 = 1649.52 Nmm.....TOOTHE-BUTT CONIDITION
ACTUATOR SPRING / TORQUE.......50.3 * 29.6 = 1488.88 Nmm....TOOTHE-BUTT CONIDITION
(6)
(6)
(7)
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