HEAVY TRUCK CALCULATION WORKSHEET
PUSHROD FORCE DETERMINATION
SHEET 1 OF 3
CASE NO.:_________________
INVESTIGATOR:______________________________
DATE:_____________________
LOCATION:______________________________COMPANY_________________
1
Measured
Stroke
AXLE /
WHEEL
2
Brake
Temp
3
Heat
Incr
4
Hot
Stroke
1 +3
5
Dyn Incr
6
Dyn
Stroke
1+3+5
7
Type
(Size)
8
Appl Air
9
Pushrod Force
(from chart)
1-Steer Lft
1-Steer Rt
2-Drive-Lft
2-Drive-Rt
3-Drive-Lft
3-Drive-Rt
4-Trl A-Lft
4-Trl A-Rt
5-Trl A-Lft
5-Trl A-Rt
6-Trl B-Lft
6-Trl B-Rt
7-Trl B-Lft
7-Trl B-Rt
NOTES:
o
o
o
o
Dynamic Increment = 0.05 + (0.034 x Time)
Temperature increment can be figured from formulas.
Air pressures should reflect what was applied at the moment of braking. (This value
should consider leaks, etc.)
Pushrod force values should be read from the charts.
HEAVY TRUCK CALCULATIONS WORKSHEETS
Sheet 2 of 3
BRAKE FORCE CALCULATIONS – S-CAM
CASE NO.__________________
INVESTIGATOR:______________________________________________DATE:_____________________
Location: ____________________________Company:____________________________
Brake Force: [ 2.0 x Pushrod Force x SlackL x LiningF x Drum Rad] x 0.6 ]
(0.5) x Tire Rolling Rad
NOTES:
o Pushrod Force found on charts looking up stroke and pressure.
o Stroke should have an Increment added to it based on estimated speed:
o 30mph - 0.13 in., 40 mph - 0.16 in., 50 mph - 0.19in., 60 mph - 0.22 in.
o Stroke can also be adjusted for heat (Done before dynamic increment added)
AXLE/WHEEL
1-Steer Lft
1-Steer Rt
2-Drive-Lft
2-Drive-Rt
3-Drive-Lft
3-Drive-Rt
4-Trl A-Lft
4-Trl A-Rt
5-Trl A-Lft
5-Trl A-Rt
6-Trl B-Lft
6-Trl B-Rt
7-Trl B-Lft
7-Trl B-Rt
Pushrod
Force
Slack
Length
Lining
Friction
Drum
Radius
Tire Roll
Radius
Attempted
Brake Force
HEAVY TRUCK CALCULATION WORKSHEETS
BRAKE EFFICIENCY CALCULATIONS
SHEET 3 OF 3
CASE NO._______________
INVESTIGATOR:______________________________________________DATE:__________________
LOCATION:___________________________________COMPANY:____________________________
AXLE/WHEEL
1
Vertical Load
2
Available
Brk Force
F* x Load(1)
3
Attempted
Brk Force Other pg.
4
Smaller of
Column 2 or
3
Locked Wheel
Yes/No
1-Steer Lft
1-Steer Rt
2-Drive-Lft
2-Drive-Rt
3-Drive-Lft
3-Drive-Rt
4-Trl A-Lft
4-Trl A-Rt
5-Trl A-Lft
5-Trl A-Rt
6-Trl B-Lft
6-Trl B-Rt
7-Trl B-Lft
7-Trl B-Rt
TOTAL LOAD:_____________________________ BRAKING FORCE:_________________________
(TOTAL COLUMN #4)
Vehicle Deceleration Rate = Braking Force / Total Load = __________________________________
TOTAL EFFICIENCY = Decel Rate / Coef of Friction = ________________________________
Passenger Car Tire-Road Coef of Friction________ x Factor for Truck Tire_______ =______________
*F = Truck Tire-Road Coef of Friction = _________ (Use in Column # 2)