Why Caster Design Matters in Safe Patient Transers
- Rick Finch
- Mar 3
- 4 min read
When evaluating mobile patient lifts, most healthcare teams focus on lifting capacity. But one of the most significant ergonomic risk factors isn’t the lift, it’s the push.
Every time a caregiver performs a transfer using a floor-based lift, they must initiate and control movement of the device while supporting a suspended patient. If push–pull forces exceed accepted ergonomic limits, spinal shear forces increase, elevating the risk of musculoskeletal injury.
The good news? Recent push–pull testing of the new EZ Effort™ lift line demonstrates that even at capacities up to 1,000 pounds, caregivers can remain within published acceptable force ranges for short-distance transfers.
Understanding Acceptable Push–Pull Force Limits in Healthcare
Ergonomic guidance used in healthcare is largely based on Liberty Mutual psychophysical research.[1] For a 25-foot movement (which reflects most patient transfers within a room), recommended limits for 75% of female caregivers are[2]:
Initial Force (to start movement): 51 lb.
Sustained Force (to keep movement going): 30 lb.
These limits assume:
Hand position at approximately 3 feet (36 inches) above the floor
Task frequency no more than once every 30 minutes
So how does a mobile lift actually perform when measured against these evidence-based limits? The only way to answer that question is through objective force testing. That’s exactly what EZ Way conducted with the EZ Effort™ lift line.
Real-World Push–Pull Testing: EZ Effort™ Lift Line
EZ Way conducted push–pull, pivot, and rolling force testing on the EZ Effort™ Lift line using standard 4" casters on a smooth concrete floor.[3] Testing began with casters positioned 90° to the direction of travel, a conservative, adverse starting condition that increases initial force.
The testing measured:
Push–Pull: Force to start movement
Pivot: Force to change direction
Rolling: Force to continue movement in the same direction
Below are the key push–pull (initial) results for the EZ Effort™ line.
1,000 lb. EZ Effort™ Lift Performance
For the 1,000 lb. EZ Effort™ Lift, the measured push–pull forces were:
250 lb. load: 15 lb.
500 lb. load: 25 lb.
600 lb. load: 28 lb.
750 lb. load: 30 lb.
1,000 lb. load: 42 lb.
At full 1,000 lb. capacity, the initial force required is 42 lb. That is:
Below the 51 lb. initial force limit for a 25-ft move
Within the full Liberty Mutual design range
Even under conservative test conditions the 1,000 lb. EZ Effort™ model keeps caregivers within accepted ergonomic limits for a typical short-distance transfer.
Performance Across the EZ Effort™ Line at Maximum Load
All EZ Effort™ models tested well within the Liberty Mutual design range.
Push–Pull at 750 lb. = 29 lb.
500 lb. EZ Effort™ Lift
Push–Pull at 500 lb. = 24 lb.
All values remain comfortably below the 51 lb. initial limit for 25-foot transfers. This demonstrates an important point:
Increased weight capacity does not have to mean increased push force, when caster technology and system design are optimized correctly.
Why Caster Technology and Lift Weight Matter
Push–pull force is influenced by:
Overall lift weight
Caster diameter and material
Swivel resistance
Bearing design
Floor surface condition
Wheel alignment
The EZ Effort™ Lift line was engineered with:
Optimized 4” casters for lower rolling and swivel resistance (While still maintain the clearance of a 3” caster)
Reduced unit weight
· Efficient rolling force even under load
The result is smoother initiation of movement and lower required push force even when lifting and moving larger patients. With the right engineering approach and technology, higher capacity and acceptable push–pull forces can coexist for typical in-room transfers.
How This Supports a Safer SPHM Program
The white paper Safe Patient Handling and Mobility (SPHM): A Process to Protect Health Care Workers
and Recipients reports that comprehensive SPHM programs using mechanical lifting devices can:
Reduce Work-Related Musculoskeletal Disorders (WMSDs) by 30%–95%
Decrease lost and restricted workday injury rates by 66%–100%
Achieve return on investment in as little as 15 months.[4]
Mobile lifts that stay inside recommended push–pull force ranges contribute to that success by:
Reducing spinal shear loads during transfers
Supporting consistent adherence to “no-lift” policies
Lowering the physical barrier to consistent equipment use
In other words, the right equipment design makes it easier for staff to do the right thing, every time.
The Bigger Picture: Engineering for Caregiver Protection
Lifting capacity is only part of safe patient handling.
Equally important is whether a lift:
Keeps push–pull forces within accepted ergonomic limits
Reduces spinal shear exposure
Minimizes cumulative musculoskeletal strain
The EZ Effort™ lift line demonstrates that mobile lifts, even up to 1,000 lb. capacity, can remain within published acceptable push–pull force ranges for typical short-distance patient transfers.
That is engineering aligned with evidence-based ergonomic standards.
Your Partner In Safe Patient Handling
Want to see the difference for yourself?
Contact us to schedule an on-site EZ Effort™ lift demonstration with an EZ Way representative.
[1] Thomas Waters, John D. Lloyd, Edward Hernandez, and Audrey Nelson, “AORN Ergonomic Tool 7: Pushing, Pulling, and Moving Equipment on Wheels,” AORN Journal 94, no. 3 (September 2011): 254–260, https://doi.org/10.1016/j.aorn.2010.09.035.
[2] The push–pull force limits cited are based on the Liberty Mutual psychophysical tables developed by Snook and Ciriello and remain widely used in healthcare ergonomic assessments. See Thomas Waters et al., “AORN Ergonomic Tool 7: Pushing, Pulling, and Moving Equipment on Wheels,” AORN Journal 94, no. 3 (September 2011): 254–260, https://doi.org/10.1016/j.aorn.2010.09.035
; and S. H. Snook and V. M. Ciriello, “The Design of Manual Handling Tasks: Revised Tables of Maximum Acceptable Weights and Forces,” Ergonomics 34, no. 9 (1991): 1197–1213.
[3] Push-pull forces will vary dependent on type of flooring material.
[4] American Industrial Hygiene Association (AIHA), Safe Patient Handling and Mobility (SPHM): A Process to Protect Health Care Workers and Recipients (Falls Church, VA: American Industrial Hygiene Association, 2024).
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