Sizing caliper disc brakes can be an easy process. The goal is to determine how much braking tque is required and finding the most cost effective and efficient brake and disc diameter package. Go to the appropriate fmulas f either industrial vehicular applications and begin. Confirm your selection by faxing the sizing wksheet, page 0, to our customer service group. INDUSTRIAL FORMULA - STOPPING i. Calculate braking tque f application involving stopping in a specified period of time. T = WK N 308t i a. Determine heat generation and dissipation by calculating Btu s per stop. Btu/stop = WK N 4,570,000 i b. Determine Btu s per hour. T = Tque, ft.-lb W = Weight of rotating member, lb. K = Radius of gyration of rotating member, ft. (see graphics below) N = RPM t = Stopping time required, seconds. i c. Determine square feet of exposed disc area sufficient enough to dissipate heat. i d. See Table 1 above to select crect disc diameter. i e. See helpful guidelines section on next page. Btu/hour = (Btu/stop)(stops/hr) BTU/hr 660 Solid cylinder about its own axis r K = r π TNt 46,680 Hollow cylinder about its own axis r 1 r K = r 1 + r Radius of gyration f geometrical fms references an axis at which the entire mass of the body may be considered as concentrated. If your application involves other geometric fms consult a reference guide such as Machinery's Handbook. ii. TABLE 1. Exposed areas, weights and BTU/hr of commonly used discs. DISC DIA. 6 5 /16 6.58.43 1.37 83.8 8.53.70 3.5 46.0 10 157.08 1.09 5.46 719.4 1 6.0 1.57 7.91 1036.0 16 40.1.79 14.07 1841.4 INDUSTRIAL FORMULA -TENSIONING Calculate braking tque f application involving tensioning constant drag. T = (L) (F) (R), inch lbs. ii a. Find Btu s per hour. Btu/hour = ii b. Calculate heat dissipation f tensioning application by determining square feet of exposed disc area required. EXPOSED AREA SQ. IN. (T) (rpm) 4.75 Btu/ hr 660* SQ. FT. WEIGHT LBS. L = Web width, in. F = Tension, lb. per in. of web width R = Maximum roll radius, in. rpm can be found by converting web velocity usually given in feet per minute (fpm). fpm rpm = C Where C = Circumference at maximum roll diameter, ft. * The constant of 660 is f a maximum disc temperature of 300. ii c. See Table 1 above to select crect disc diameter. ii d. See Helpful Guidelines section on next page. MAX. BTU/HR @ 300 F
VEHICULAR FORMULA i. Calculate braking tque (Dynamic). T = WR [ ] + a g D b i. Calculate braking tque (Parking). [] b T = WR D T = Tque, ft.-lb./axle, vehicle wheel W = Weight on axle including weight transfer, if any, vehicle wheel. R = Loaded tire radius, ft. g = 3. b = % of grade D = Gear reduction, if drive line mounted a = Deceleration rate, ft/sec. If a is not known solve: V a = = t V S V = Velocity of vehicle, ft./sec. at moment of applying brake. t = Stopping time required, seconds. S = Stopping distance of vehicle, ft. i a. i b. i c. i d. i e. i f. Determine heat generation and dissipation. E = WV g Calculate Btu s per hour generated. Btu/hr. generated = Determine square feet of exposed disc area sufficient enough to dissipate heat. See Table 1 on previous page to determine disc diameter. See Helpful Guidelines section. E = Kinetic Energy, ft. ib. W = Weight of axle, vehicle wheel, lb. V = Speed of vehicle, ft./sec. (E) (stopping frequency/hr.) Btu/hr 660 778 After determining the caliper disc brake and disc diameter necessary f your application, please contact W.C. Branham f confirmation.all vehicular applications must be approved by W.C. Branham in writing. Helpful guidelines 1. F best service life do not exceed disc temperature of 300 F.. Fmulas f heat dissipation are based on 0 F temperature rise and 80 F ambient. 3. Since the amount of heat dissipated per hour by the disc at a given temperature above ambient is considered as being directly proptional to the exposed area of the disc, disc thickness should be kept small. Standard thicknesses are 5/3" and 1/4". Disclaimer: All fmulas and graphs depicted in this catalog are theetical. W.C. Branham Inc. does not imply state in any terms that fmulas and graphs are crect f any given application. The fmulas and graphs are supplied as a guide only. It is suggested that each application be prototyped and tested. All specifications subject to change without notification. 3
FRICTION MATERIAL LIFE EXPECTANCY Figure 1, at right, depicts friction material life per cubic inch in hsepower hours. To determine life in hours of a brake brakes, see below. 300 Figure 1. General Industrial Molded Friction Material i. Find life in hours of brake brakes (most commonly used in tensioning dragging applications) i a. Ft. lb/hr = (Btu/hr) (778) Determine hsepower hours per hour. Hp hrs/hr = Ft. lb./hr 1,980,00 Life, H.P. HRS/ CU. IN. 50 0 50 50 i b. Locate Table below, and find the cubic inches of wearable material f various WCB caliper disc brakes. Calculate life in hours. Life in hours = (# of brakes) (M) (HP hrs/in 3 ) HP hrs/hr 0 0 00 00 300 400 500 600 700 800 Disc Temperature, F M = Cubic inches of wearable material taken from Table f desired caliper disc brake. TABLE. Wearable friction material of WCB brakes 38 Series.46 Cubic inches 47 Series.83 Cubic inches 47 Series (retractable).48 Cubic inches 00 Series 1.66 Cubic inches 00 Series (retractable).95 Cubic inches 493 Series 3.45 Cubic inches 96 Series 19.0 Cubic inches FRICTION MATERIAL LIFE EXPECTANCY If necessary, find the amount of life in stops of a brake brakes. Kinetic energy can be removed from a rotating mass brought to rest. Calculate as follows: (π) (T) (N) (t) E ft. lb = 60 (WK ) (N ) E ft. lb = 587 i. Calculate Hsepower hours per stop. E Hp hrs/stop = 1,980,000 i a. Find life in stops (# of brakes) (M) (HP hrs/in 3 ) Life in stops = HP hrs/stop M = Cubic inches of wearable material taken from Table f desired caliper disc brake. Note: Friction material life expectancies are calculated estimates and do not take into consideration of any feign contaminants which may reduce wear life. It is suggested that when life must be known accurately, field tests should be conducted. 4
T E C H N I C A L D A T A TABLE 3. Cam travel data f WCB mechanical disc brakes. M38 AND M47 SERIES BRAKES a. 15 maximum travel when friction pads are new and with 1/3" gap on each side of disc. b. Periodic tightening of lock nut will reduce travel of level and will allow 1/4" wear on each friction pad. c. 90 maximum travel after 3/16" wear on each friction pad and without intermediate tightening of lock nut. Braking tque (inch/lb) H / P 38 SERIES H / P 47 SERIES H / P 00 SERIES 70 lb. of fce per PSI x Braking 35 lb. of fce per PSI x Braking 144 lb. of fce per PSI x Braking 7 lb. of fce per PSI x Braking M00 SERIES BRAKES 88 lb. of fce per PSI x Braking a. Gap between friction pad faces and disc when new =.048" total. H 493 SERIES 144 lb. of fce per PSI x Braking b. Angular movement of lever required to actuate brake when new = 7 30 c. Maximum axial movement without intermediate adjustment =.387". 353 lb. of fce per PSI x Braking 11 lb. of fce per PSI x Braking d..08" total wear allowed befe adjustment of each side. H/P 96 SERIES 693 lb. of fce per PSI x Braking PRESSURE RATINGS 347 lb. of fce per PSI x Braking 38 Series 0 PSI Maximum 47 Series 0 PSI Maximum 00 Series 1500 PSI Maximum 493 Series 1500 PSI Maximum 96 Series 0 PSI Maximum M38/ M47 SERIES.69 x Lever Fce (lb.) x Braking. 1.75 x Lever Fce (lb.) x Braking. MECHANICAL BRAKE LEVER FORCES M00 SERIES 38 Series 450 lb. Maximum 47 Series 450 lb. Maximum 00 Series 580 lb. Maximum 7.45 x Lever Fce (lb.) x Braking. 3.73 x Lever Fce (lb.) x Braking. 5
S I Z I N G W O R K S H E E T Sizing wksheet f industrial applications only,consult facty on vehicular applications. Complete the following.keep this page as an iginal by copying befe proceeding. Your Name: Company: Title: Address: City: State: Zip Code: Phone ( ) Fax ( ) Describe the application: Application data: Weight of rotating member, lb........................................ Radius of gyration of rotating member, ft............................... RPM.......................................................... Stopping time required, seconds...................................... # of stops / minute................................................ Maximum allowable disc diameter. in.................................. Disc thickness, in................................................. Actuation: Mechanical Pneumatic Hydraulic Spring Applied Amount of pressure available, psi..................................... Back pressure, if any, psi............................................ Type of fluid.................................................... Ambient temperature.............................................. Desired friction pad life............................................ Tensioning dragging application: Web width, in.................................................... Amount of tension per inch of web width, lb............................. Maximum roll radius, in............................................ Web velocity, feet per minute........................................ Please submit this fm via fax 715.46.1400. Attention: Customer Service Group. We will acknowledge receipt of your criteria promptly. Our recommendation is based on infmation supplied by the customer. Final acceptance and approval is the responsibility of the customer. Each application should be prototyped and tested. 0