A loaded cart’s push force cannot be determined from weight and a floor description alone. It also depends on the wheels, bearings, caster alignment, and whether the cart is starting, rolling straight, turning, or crossing a floor defect. Starting resistance and steady rolling resistance are different measurements; neither substitutes for the force required to swivel the casters.
The reference table below estimates sustained force for an entire loaded cart rolling straight at constant speed. It uses explicitly assumed resistance coefficients and grades—not measured performance for a particular wheel material or floor. Use it to compare scenarios, then confirm the actual cart on its operating route.
Push Force Reference Table
Total loaded weight includes the cart, attached equipment, and payload. It is not payload alone, a single caster’s load, or the sum of the casters’ rated capacities.
Each cell shows force in lbf, followed by N in parentheses.
| Total loaded weight, lbf | Level floor, (C_{\mathrm{rr}}=0.01) | Level floor, (C_{\mathrm{rr}}=0.03) | Level floor, (C_{\mathrm{rr}}=0.06) | 2% uphill grade, (C_{\mathrm{rr}}=0.03) | 5% uphill grade, (C_{\mathrm{rr}}=0.03) |
|---|---|---|---|---|---|
| 250 | 2.5 (11) | 7.5 (33) | 15.0 (67) | 12.5 (56) | 20.0 (89) |
| 500 | 5.0 (22) | 15.0 (67) | 30.0 (133) | 25.0 (111) | 40.0 (178) |
| 1,000 | 10.0 (44) | 30.0 (133) | 60.0 (267) | 50.0 (222) | 79.9 (355) |
| 2,000 | 20.0 (89) | 60.0 (267) | 120.0 (534) | 100.0 (445) | 159.8 (711) |
The coefficients 0.01, 0.03, and 0.06 are hypothetical comparison inputs. They are not recommended values for polyurethane, rubber, concrete, carpet, or any other material pairing. The table assumes continuous wheel contact, no brake drag, no acceleration, and a push parallel to the travel surface. It does not include starting, turning, threshold-crossing, or stopping forces.
Values are rounded to 0.1 lbf and whole N for reproducibility, not to imply that field resistance is known that precisely. The lbf and N values are rounded independently from the unrounded calculation.
At a fixed coefficient and grade, doubling total weight doubles the modeled force. Changing caster count alone does not change the table result because the model uses one effective resistance coefficient for the whole cart. A different caster layout may change load distribution and maneuvering resistance, so its coefficient and measured forces still need confirmation.
How Floor Condition Changes the Reference Value
A label such as “smooth concrete” does not establish a coefficient. Wheel diameter, tread geometry, hardness, resilience, bearings, and the running surface all affect resistance. Blickle’s wheel-series technical guide identifies these factors and distinguishes starting, rolling, and swivel resistance.
Use the following table to decide which input or measurement the route requires.
| Floor or route condition | What to establish | How to use the reference table |
|---|---|---|
| Clean, smooth, level floor | Resistance for the actual wheel, bearing, load, and surface combination | Use a level-floor column only if its assumed coefficient matches supported data or a representative measurement. |
| Rough or worn floor without distinct obstacles | Steady rolling force over representative sections, including variation along the route | Derive an effective coefficient from level-floor measurements rather than assigning one from appearance. |
| Carpet or another deformable surface | Performance of the actual wheel on the actual surface at the intended load | Do not transfer a coefficient measured on steel or concrete without checking it. |
| Continuous uphill grade | Rise/run grade and an applicable rolling-resistance input | Add the gravity component using the incline formula below. |
| Joints, cracks, thresholds, dock-plate edges, or debris | Separate crossing-force peaks and the relevant obstacle geometry | Do not treat a steady rolling-force estimate as the crossing force. |
| Wet, oily, or dusty floor | Both cart resistance and the operator’s available footing | A low calculated rolling force does not establish that the operator can control the cart. |
CCOHS notes that damaged floors can catch wheels, while dusty, oily, or wet floors can reduce the handler’s traction. It also distinguishes the effort required to move uphill from the effort needed to control a loaded cart downhill.
Manufacturer comparisons also have test boundaries. Blickle reports measuring wheel rolling resistance on a level, smooth steel surface free of dirt and obstacles, at 4 km/h, +20°C, and two-thirds of maximum load capacity. Those conditions support comparisons among its wheel series; they do not establish a universal coefficient for a warehouse floor. A qualitative rating such as “excellent” is not a numeric coefficient.
Formula, Inputs, and Units
The reference table uses a force balance along the travel surface:
[
F_{\mathrm{run}}
=
C_{\mathrm{rr}}W\cos\theta
+
W\sin\theta
]
Where:
- (F_{\mathrm{run}}) is the sustained uphill push force.
- (C_{\mathrm{rr}}) is a dimensionless effective rolling-resistance coefficient.
- (W) is the gravitational weight of the entire loaded cart.
- (\theta) is the uphill angle from horizontal.
Use the same force units for (W) and (F_{\mathrm{run}}): lbf produces lbf, and N produces N. For mass entered in kg, first calculate weight as (W=mg), using (g=9.80665\ \mathrm{m/s^2}). In US measurements, distinguish a cart’s mass in lb from its weight force in lbf; the table labels the force explicitly.
Floor grade is rise divided by horizontal run:
[
s=\frac{\text{grade (%)}}{100},
\qquad
\theta=\arctan(s)
]
Substituting grade directly gives:
[
F_{\mathrm{run}}
=
W\frac{C_{\mathrm{rr}}+s}{\sqrt{1+s^2}}
]
A 5% grade means 5 units of rise per 100 units of horizontal run—not a 5° slope.
For shallow grades, the approximation
[
F_{\mathrm{run}}\approx W(C_{\mathrm{rr}}+s)
]
is often convenient, but the table uses the full trigonometric expression. Force conversion is:
[
1\ \mathrm{lbf}=4.4482216152605\ \mathrm{N}
]
Worked example: a 1,000 lbf cart on a 2% grade
Assume:
- Total loaded weight: 1,000 lbf.
- Effective rolling-resistance coefficient: 0.03.
- Uphill grade: 2%.
- Straight, constant-speed travel with the push parallel to the incline.
Then:
[
F_{\mathrm{run}}
=
1{,}000
\frac{0.03+0.02}{\sqrt{1+0.02^2}}
=
49.990\ \mathrm{lbf}
]
[
F_{\mathrm{run}}
=
49.990\times4.4482216152605
=
222.367\ \mathrm{N}
]
The reference value is therefore 50.0 lbf, or 222 N. On a level floor with the same assumed coefficient, the estimate is 30.0 lbf. The grade adds approximately 20 lbf in this example.
This calculation assumes that resistance remains proportional to normal load. It does not establish how the actual wheels behave as load, speed, temperature, or surface conditions change.
Check the resistance parameter before using it
The coefficient used here is a force ratio:
[
C_{\mathrm{rr}}=
\frac{F_{\mathrm{rolling}}}{N_{\mathrm{normal}}}
]
It has no units. Some engineering references instead use a rolling-resistance parameter with units of length. Do not enter a value in inches or millimeters into a dimensionless coefficient field. Obtain the source’s equation and confirm whether wheel radius, diameter, bearing losses, or other terms are required.
A coefficient inferred from a whole-cart test includes the resistance present during that test. Do not add a separate bearing or caster allowance if that would count the same loss twice.
Measure Starting and Running Force Separately
A rolling-force calculation does not predict the initial peak after a cart has been parked or the force needed to realign swivel casters. Blickle defines starting resistance as the force required to initiate movement and swivel resistance as the resistance associated with aligning swivel casters in the direction of travel.
For a useful field comparison:
- Record the equipment and load. Note the cart ID, total loaded weight, load position, wheel diameter and material, bearing type, caster layout, and wheel count. Record pneumatic tire pressure where applicable.
- Inspect before measuring. Check for brake contact, loose or damaged wheels, trapped material, and obvious bearing or swivel problems. OSHA identifies malfunctioning wheels and improper tire inflation as contributors to increased handling effort.
- Use a suitable force gauge. Use an instrument and attachment rated for the expected force and compatible with the cart. Record its calibration status, measurement direction, and attachment height. For comparison with the formula, measure force parallel to the travel surface; an angled reading is not directly equivalent.
- Separate the operating events. Record the starting peak with casters aligned, the starting peak from a representative parked orientation, steady straight-line rolling force, and turning or crossing peaks as separate results.
- Repeat under matched conditions. Keep the load, route, speed, caster orientation, and rest period consistent. Record the number of trials and the observed range rather than reporting only the lowest reading.
Do not initiate a manual test where the load, slope, or available stopping arrangement could allow uncontrolled movement. Use a controlled assessment or suitable powered assistance instead.
On a level surface, an effective coefficient can be estimated from measured steady force:
[
C_{\mathrm{eff}}
=
\frac{F_{\mathrm{run,measured}}}{W}
]
For example, a hypothetical 600 lbf loaded cart requiring 18 lbf to roll steadily has:
[
C_{\mathrm{eff}}=\frac{18}{600}=0.030
]
That ratio describes the tested cart and conditions. A starting peak should be recorded separately, not substituted for steady force in this calculation. An uphill measurement also includes gravity, so dividing it by weight without correcting for grade overstates rolling resistance.
Compare Force With a Task-Specific Effort Budget
A force reference table describes mechanical demand. It does not establish whether that demand is acceptable for every operator or work cycle.
OSHA’s electrical-contractor materials-handling eTool recommends limiting loads so that necessary pushing force is less than 50 pounds. It also addresses posture, handles, wheel condition, floor condition, and footing. That recommendation is screening guidance in its stated context, not a universal sustained-force pass/fail criterion.
CCOHS’s handcart guidance separately discusses initial and sustained forces and identifies distance, duration, direction, stopping effort, and human factors as relevant. It does not support replacing that assessment with one force value for every task.
When a task-specific force budget has been selected through an appropriate assessment, calculate its utilization as:
[
\text{Budget utilization (%)}
=
100\frac{F_{\mathrm{task}}}{F_{\mathrm{budget}}}
]
Compare like with like: starting peak against an initial-force budget, and running force against a sustained-force budget applicable to the actual duration and repetition.
For illustration only, the 50.0 lbf running-force example would use approximately 125% of an assumed 40 lbf sustained-force budget. The 40 lbf value is a hypothetical comparison input, not a recommended limit. A result below 100% would still leave turning, stopping, posture, footing, and the full work cycle to assess.
Use the Calculators Without Mixing Their Outputs With Measurements
The Cart Push Force Calculator provides fields for loaded cart weight, a rolling-resistance coefficient, floor grade, and a comparison guideline. Its page states that breakaway force, floor defects, wheel wear, and bearing condition are not modeled separately. An assumed coefficient and a displayed guideline therefore remain inputs to a screening estimate—not measured resistance or an ergonomic approval.
The Caster Push Effort Budget accepts required push force, operator body weight, handle height, continuous push time, and repetition frequency. Its displayed allowances and verdicts are model outputs, not measured operator capacity; body weight alone does not establish strength. Use the result to flag a task for review, not to certify a person’s ability to perform it.
For maintenance or procurement comparisons, keep a separate record for each configuration:
| Record item | What to retain |
|---|---|
| Equipment and loading | Cart ID, total loaded weight, load position, wheel/caster configuration, and condition |
| Route | Surface, grade, joints, contamination, temperature where relevant, and travel direction |
| Force results | Starting peak, steady rolling force, turning and crossing peaks, units, trial count, and range |
| Calculated estimate | Coefficient, its definition and source, formula used, grade, and resulting lbf and N |
| Effort comparison | Selected budget, its basis, applicable duration and repetition, and unresolved task factors |
| Traceability | Measurement date, instrument details, test method, and manufacturer document or report revision |
Keep measured results, manufacturer data, and assumed scenarios visibly distinct. A lower calculated running force is useful for comparing options, but a replacement wheel or revised route should be evaluated under matched operating conditions before its handling benefit is accepted.