Pallet jack and cart push force calculator

F_wheel = f x W / R; F_total = sum of F_wheel = f x total_weight / R when every wheel has the same radius and the same tread

Hamilton: f is the coefficient of rolling friction in the same unit as the radius R; its table is for wheels on a steel floor at 3 mph. Summing the wheels is Hamilton's step 5; folding equal wheels into one line is our arithmetic.

Worked example: Hamilton: 4,800 lb trailer, 4 wheels, 8 in polyurethane (f=0.047 in): 0.047 x 1200 / 4 = 14.1 lb per wheel; x4 = 56.4 lb.

lookup (inches, steel floor, 3 mph): forged steel 0.019; cast iron 0.021; hard rubber 0.303 (as printed); polyurethane 0.030-0.057; cast nylon 0.027; phenolic 0.026

Hamilton table on page 3 (an image: read the rendered page). Polyurethane has a range depending on the material selected; Hamilton uses 0.047 for its 8 in polyurethane 85A example. The calculator does not offer hard rubber.

Worked example: Hamilton: 8 in polyurethane 85A, f = 0.047 in.

F_start = 2 to 2.5 x F_sustained

Hamilton: the force to start motion is in general 2 to 2.5 times the sustaining force.

Worked example: Hamilton: 56.4 lb rolling -> about 115 lb starting.

initial ≤ 50 lb occasional, ≤ 35 lb frequent (>1/min); sustained ≤ 35 lb occasional, ≤ 20 lb frequent

Caster City states these as thresholds that general consensus supports for occasional manual cart handling; frequent means more than once per minute.

Worked example: Our comparison: Hamilton's 115 lb starting force is over the 50 lb occasional initial-force threshold.