Solving Wheel Hop in Heavy Equipment

[MikePhua]

What Wheel Hop Really Means
Wheel hop refers to the rhythmic bouncing or oscillation of drive wheels during acceleration or under load. In heavy equipment—especially backhoes, loaders, and graders—this phenomenon is more than a nuisance. It can reduce traction, damage driveline components, and compromise operator control. Unlike suspension bounce, wheel hop is typically caused by drivetrain or tire-related issues that create a feedback loop between torque delivery and surface resistance.
Terminology notes:

• Wheel hop: Vertical oscillation of drive wheels caused by torque imbalance or surface irregularities.
  
• Driveline lash: Excessive play between drivetrain components, often contributing to hop.
  
• Torque spike: Sudden increase in rotational force, which can trigger wheel hop if not absorbed properly.
  

Root Causes of Wheel Hop
Several mechanical and operational factors can lead to wheel hop in heavy machinery:

• Tire pressure imbalance: Uneven inflation causes differential traction, especially on hard surfaces.
  
• Worn pivot bushings or linkages: Excessive play in the rear axle or loader arms can amplify oscillation.
  
• Loose or degraded dampers: Hydraulic or mechanical dampers that control axle movement may fail to absorb shock.
  
• Improper ballast distribution: Lack of counterweight or uneven load shifts the center of gravity, increasing bounce.
  
• Transmission backlash: Worn gears or couplings can create torque surges that feed into the wheels.
  
• Surface resonance: Operating on certain hard-packed surfaces can trigger harmonic vibration at specific speeds.
  

In one case from a quarry in Alberta, a loader experienced severe wheel hop when reversing uphill with a full bucket. After inspecting the rear axle, technicians found worn bushings and a cracked torque rod mount. Replacing these components eliminated the hop entirely.
Equipment Spotlight Case 580N Backhoe Loader
The Case 580N is a modern evolution of the iconic 580 series, introduced in the 1960s. Case Construction Equipment, founded in 1842, has sold over 500,000 backhoes globally. The 580N features:

• Operating weight: Approx. 17,000 lbs
  
• Engine: 3.4L turbocharged diesel, 74 hp
  
• Transmission: Powershift with 4 forward and 4 reverse gears
  
• Rear axle: Heavy-duty planetary drive with differential lock
  
• Tire size: 19.5L-24 rear, 12L-16.5 front
  

Wheel hop in the 580N is rare but can occur under specific conditions, especially when tires are mismatched or the rear axle bushings are worn. Case recommends checking tire pressure weekly and inspecting axle mounts every 500 hours.
Diagnostic Checklist for Wheel Hop
To isolate the cause of wheel hop, follow a structured inspection:

• Check tire pressure and match across axles
  
• Inspect rear axle bushings and torque rods
  
• Examine transmission mounts and driveline couplings
  
• Test hydraulic dampers for resistance and leakage
  
• Verify ballast placement and load distribution
  
• Observe hop behavior under different speeds and surfaces
  

Use slow-motion video or vibration sensors to capture hop frequency. If the hop occurs at a consistent speed, it may be surface-induced resonance. If it varies with load, it’s likely mechanical.
Solutions and Preventive Measures
Once diagnosed, wheel hop can be mitigated through targeted repairs and adjustments:

• Replace worn bushings and dampers
  
• Balance tire pressure and replace mismatched tires
  
• Add counterweights or redistribute load
  
• Tighten driveline couplings and inspect gear lash
  
• Avoid high-speed operation on hard-packed surfaces
  
• Use radial tires with better shock absorption
  

A contractor in Texas retrofitted their fleet with nitrogen-filled tires and added rear ballast plates. Wheel hop incidents dropped by 80%, and tire wear improved significantly.
Operator Stories and Field Wisdom
Veteran operator Mike “Steeltoe” Ramirez recalled a grader that bounced violently during shoulder work. “It felt like the rear end was trying to jump off the road,” he said. After checking everything else, they found the rear tires had 20 psi difference. Equalizing the pressure solved the issue instantly. “Sometimes it’s the simplest thing,” he added.
Another story from a logging crew in Oregon involved a loader that hopped only when backing downhill. The culprit was a cracked rear torque rod bracket that flexed under reverse torque. Welding a new bracket restored stability.
Recommendations for Fleet Managers

• Include tire pressure checks in daily pre-op inspections
  
• Train operators to recognize hop and report it early
  
• Maintain a log of hop incidents with speed, load, and surface notes
  
• Schedule axle and bushing inspections every 1,000 hours
  
• Use vibration sensors on high-value machines to monitor oscillation trends
  

Conclusion
Wheel hop in heavy equipment is a solvable problem with mechanical, hydraulic, and operational roots. By understanding its causes and applying targeted solutions, operators and technicians can restore smooth performance and protect critical components. Whether it’s a backhoe on a city street or a loader in a quarry, eliminating wheel hop means safer, more efficient work—and fewer surprises on the job.