Haldex Hydraulic Motors and Their Role in Mobile Equipment Systems

[MikePhua]

The Haldex Brand and Its Fluid Power Legacy
Haldex, originally founded in Sweden in the early 20th century, built its reputation on precision fluid control systems for commercial vehicles and industrial machinery. While best known for air brake components and trailer control valves, Haldex also developed a line of hydraulic motors and pumps used in mobile equipment, agricultural machinery, and specialty applications. Their hydraulic motors were compact, efficient, and designed for high torque output in low-speed environments.
Although Haldex eventually divested its hydraulic division to focus on vehicle dynamics and brake systems, many of its motors remain in service today. These units are often found in older sweepers, compact loaders, and specialty conveyor systems, where reliability and simplicity are paramount.
Terminology Notes

• Hydraulic Motor: A device that converts hydraulic energy into mechanical rotation.
  
• Gerotor Motor: A type of hydraulic motor using an internal gear set for smooth torque delivery.
  
• Displacement: The volume of fluid required to turn the motor one revolution, measured in cubic inches or cc.
  
• Torque Output: The rotational force produced by the motor, typically expressed in lb-ft or Nm.
  
• Case Drain: A low-pressure return line that prevents pressure buildup in the motor housing.
  

Common Applications and Performance Characteristics
Haldex hydraulic motors were typically used in:

• Conveyor belt drives
  
• Auger systems in agricultural spreaders
  
• Wheel drives in compact sweepers
  
• Rotary brushes in snow removal equipment
  
• Winch and hoist systems
  

Performance specs varied by model, but typical features included:

• Displacement: 8–25 cu in/rev
  
• Max pressure: 2,500–3,000 PSI
  
• Max speed: 1,000–2,500 RPM
  
• Torque: 150–600 lb-ft depending on displacement
  
• Mounting: SAE A or B flange, 2-bolt or 4-bolt patterns
  

In one municipal fleet in Ohio, a Haldex motor was used to power the brush head on a sidewalk sweeper. After 12 years of service, the motor was rebuilt with new seals and continued operating through winter salt and debris.
Troubleshooting and Failure Modes
When a Haldex motor begins to fail, symptoms may include:

• Reduced torque or sluggish rotation
  
• Excessive heat buildup in the motor body
  
• Leaking seals or fluid around the shaft
  
• Whining or grinding noises during operation
  
• Motor stalls under load or fails to start
  

Common causes:

• Internal wear of the gerotor set or bearing surfaces
  
• Contaminated hydraulic fluid causing scoring
  
• Seal degradation due to heat or chemical exposure
  
• Case pressure buildup from blocked drain line
  
• Shaft misalignment or overhung load stress
  

In one repair shop in Alberta, a Haldex motor used on a grain auger was found to have scored rotor teeth due to contaminated fluid. After flushing the system and replacing the motor, performance returned to spec.
Rebuild Strategy and Parts Sourcing
Although Haldex no longer manufactures hydraulic motors, many units can be rebuilt using aftermarket kits or donor components. Rebuild steps include:

• Disassemble motor and inspect rotor, stator, and wear plates
  
• Replace shaft seals, O-rings, and thrust washers
  
• Clean all internal surfaces with solvent and lint-free cloth
  
• Reassemble with torque specs and test under load
  
• Verify case drain function and check for leaks
  

Recommended upgrades:

• Install magnetic suction filter to catch metal debris
  
• Use synthetic hydraulic fluid for better thermal stability
  
• Add pressure gauge to monitor inlet and outlet conditions
  
• Replace hoses with abrasion-resistant sleeves
  

In one restoration project in Pennsylvania, a Haldex motor powering a conveyor was rebuilt using a seal kit sourced from a hydraulic supplier specializing in legacy components. The technician added a case drain filter and extended the motor’s service life by five years.
Replacement Options and Cross-Compatibility
If rebuilding is not feasible, replacement motors can be sourced from brands offering similar specs:

• Parker Hannifin
  
• Eaton Char-Lynn
  
• White Drive Products
  
• Danfoss
  
• M+S Hydraulic
  

To match performance:

• Measure flange and shaft dimensions
  
• Confirm displacement and pressure rating
  
• Verify rotation direction and port configuration
  
• Check mounting bolt pattern and pilot diameter
  

In one equipment yard in Arkansas, a Haldex motor was replaced with a White RS series unit after verifying torque and speed compatibility. The swap required minor hose rerouting but restored full function.
Final Thoughts
Haldex hydraulic motors may no longer be in production, but their legacy lives on in machines that still rely on their torque, simplicity, and durability. Whether rebuilding a worn unit or sourcing a compatible replacement, understanding the motor’s role in the system is key to keeping equipment moving. In the rhythm of hydraulic motion, the motor isn’t just a component—it’s the drive behind the task.