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Servomotor Brake Selection Example

The brake mounted between a servo motor and a 145TC-flanged gearbox is required to perform a dynamic stop of a gantry moving in the “X” axis, within (5) seconds. The 18 foot long gantry travels at 120 inches per second and carries a 3500 pound load. The driving/stopping forces are driven through a 40 tooth, 14mm pitch sprocket.

B

RAKE

S

ELECTION

C

ALCULATIONS Given: Gearbox Ratio= 12.19:1 Sprocket Diameter= 7.0 inches, 3.50 inch radius Velocity= 120 feet per second or 10 feet per minute Weight of loaded gantry= 3500 pounds Required Stop Time= 5 seconds Rated Brake Torque= 200 inch pounds

(1)(2)(3)(4)

Energy per Stop (E) = ½ MV
2 Torque (Tgb) at the output side of the gearbox (Rated Brake Torque x Gearbox Ratio) Tgb = 200 x 12.19 = 2438 in-lb Mass (M) = W/32.2 W=Weight of the load 32.2=Acceleration of gravity M = 3500/32.2 = 109 lbs E = 1/2(109)10
2 = 5435 lb-ft
2 Stop Time (t) = Velocity (V) of the gantry divided by the Deceleration Rate (a) in feet per second squared a = 32.2 (F)/ W V = Velocity in feet per minute = 10 a = 32.2 (697)/ 3500 = 6.4 fps squared t = 10/6.4 = 1.6 seconds Force (F) in pounds exerted on the drive sprocket (Torque (Tgb) at the output side of the gearbox divided by the Sprocket Radius) F = 2438/3.5 = 697 lbs

R

ECOMMENDED

E

CLIPSE TM

S

ERVOMOTOR

B

RAKE Size 4, 200 inch pound rated brake Input Flange Data: Bolt Circle: 165 mm, Bore: 24mm Output Flange and Shaft Data: NEMA 145TC
In accordance with Nexen’s established policy of constant product improvement, the specifications contained in this document are subject to change without notice. Technical data listed in this document are based on the latest information available at the time of printing and are also subject to change without notice. For current information, please consult: www.nexengroup.com Nexen Group, Inc. 560 Oak Grove Parkway Vadnais Heights, MN 55127800.843.7445Fax: 651.286.1099www.nexengroup.com ISO 9001 Certified ©2006 Nexen Group, Inc. 21215-B-0306