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Rail Brake Sample Calculations for Emergency Stops

SAMPLE DATA Brake ModelBrake Force (F)Brake Engagement Time (t
e )Acceleration of Gravity (g)Mass of Load (m)Load Velocity (V) RB251000 N0.050 seconds9.8 m/s
2 45.4 kg0.50 m/s HORIZONTAL TRAVEL(X and Y axis) VERTICAL TRAVEL(Z axis) Dynamic Stopping Time (in seconds) Dynamic Stopping Time t
s = m • Vt t
s = (F • t
e ) + (m • V)t (F – m • g)
s = 45.4 • 0.50 = 0.023 seconds
s = (1000 • 0.050) + (45.4 • 0.50) = 0.131 seconds F (1000 – (45.4 • 9.8) Stopping Distance (in meters) at full brake force Stopping Distance (d
s ) at full brake force d
2 s = 0.5 • m • V Step A = 0.5(g – F\m) t
s2 F
2 = -.105Step B = [F/m (t d
2 s = 0.5 • 45.4 • 0.50 = 0.006 meters 1000
e ) + V]t
s = [1000/45.4 (0.050) + 0.50]0.131 = 0.210Step C = 0.5(F/m)t d
e2 = 0.5(1000/45.4)0.050
2 = 0.028d
e = V • t
e d
e = 0.5 • 0.050 = 0.025 meters
s = A + B – C= - . 105 + .210 - .028= 0.077 meters or 77 mm F Total Travel Distance Total Travel Distance d d
T = d
s + d
e d
T = 0.006 + 0.025 = 0.031 meters or 31 mm
T = d
s = 0.077 meters or 77 mm = 0.5(9.8 – 1000\45.4)0.131 In this example, the load will travel 31 mm [1.22 in] from the time the RB25 engages until the system is brought to a complete stop. Distance of Travel During Brake Engagement In this example, the load will travel 77 mm [3.03 in] from the time the RB25 engages until the system is brought to a complete stop.
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: 651.286.1099 www.nexengroup.com Nexen has sales offices throughout the United States, Europe, Japan, and Australia. ISO 9001 Certified©2006 Nexen Group, Inc.L-21194-G-0806