Disk and Shoe Brake Equations and Calculators

Related Resources: calculators



Disc Brake Calculator
A sectional view of a generic disc brake with calipers is illustrated right.











Calculate Brake Torque Capacity	Input
Clamping force, F =		lbf
Coefficient of friction, μ =		-
Caliper mean radius, Rd =		in
Number of calipers, N =		-

	Calculation
Braking torque, T =	2μFNRm
		in-lbf


Shoe Brake Calculator
Stopping capacity is proportional to the normal force of brake shoe against the drum and coefficient of friction.















Calculate Brake Torque Capacity	Input
Coefficient of friction, f =
Brake shoe face width, w =		in
Drum internal radius, Rd =		in
Shoe mean radius, Rs =		in
Shoe heel angle, A1 =		degrees
Shoe angle, A2 =		degrees
Shoe mean angle, Am =		degrees
Right shoe maximum shoe pressure, Pmr =		lbf/in^2
Left shoe maximum shoe pressure, Pml =	150	lbf/in^2
C =		in

	Calculation
X =	(Rd - RdCos(A2)) - (Rs/2)Sin^2(A2))
X =
Right shoe friction moment, Mr =	((fPmwRd)/(Sin(Am))(X)
Mr =		in-lbf

Y =	(0.5A2) - (0.25Sin(2*A2))
Y =
Right normal forces moment, Mn =	((PmwRdRs)/(Sin(Am))(Y)
Mn =		in-lbf

Brake cylinder force, P =	(Mn - Mr) / C
Answer: P =		lbf

Z =	((Cos(A1)-Cos(A2)) / Sin(Am)
Z =
Right shoe brake torque capacity, Tr =	fPmwRd^2(Z)
Tr =		in-lbf