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The Case 1845C skid steer loader has earned a reputation as one of the most durable and best‑selling machines in the compact equipment market. Introduced in the late 1980s and produced into the early 2000s, the 1845C became a cornerstone of Case’s skid steer lineup, with estimated global sales exceeding 70,000 units. Its longevity is due in part to its simple mechanical design, robust hydraulic system, and the reliability of components such as the Danfoss OMT‑series wheel motors.
Owners who maintain these machines today often encounter the need to reseal or rebuild the wheel motors, especially as the machines age past 20 or 30 years. One of the most important but frequently misunderstood aspects of this process is the timing of the wheel motor during reassembly. Improper timing can cause the motor to run backward or operate inefficiently, even if the machine appears functional. This issue was highlighted when a technician discovered misaligned internal ports and blown O‑rings during a reseal job.
The following article explains the design of the wheel motors, the importance of timing, common symptoms of misalignment, and practical guidance for owners and mechanics.
Background of the Case 1845C and Its Hydraulic Drive System
The Case 1845C uses a hydrostatic drive system, meaning each wheel is powered by hydraulic motors rather than mechanical axles. This design allows for zero‑radius turning, high torque at low speeds, and simplified drivetrain maintenance.
Key characteristics of the 1845C drive system include:
This design is known for high torque output, smooth operation, and long service life. However, it requires precise internal alignment during reassembly.
Why Timing Matters in Danfoss OMT Wheel Motors
During a rebuild, the motor must be reassembled so that the rotor, gerotor set, and port plate are aligned correctly. If these components are out of time, the hydraulic flow will not match the intended rotation direction.
Consequences of incorrect timing include:
Common Symptoms of Wheel Motor Seal Failure
As these machines age, seal kits become a routine maintenance item. Symptoms of failing seals include:
Understanding the Port Alignment Issue
Inside the OMT motor, several ports and channels direct hydraulic fluid through the rotor assembly. These ports must align perfectly with the corresponding openings in the housing.
If the ports are misaligned:
Recommended Steps for Proper Wheel Motor Timing
Although specific service manuals provide exact diagrams, the general principles of timing a gerotor motor include:
Additional Tips for Successful Reassembly
Owners and mechanics often share practical advice based on years of experience:
A Brief Look at Danfoss and the OMT Motor Line
Danfoss, founded in Denmark in 1933, has become one of the world’s leading manufacturers of hydraulic components. The OMT series, introduced decades ago, is widely used in agricultural, construction, and industrial machinery.
Key advantages of the OMT 250 motor include:
A Real‑World Example of Weather‑Driven Urgency
In one instance, a technician working on a wheel motor rebuild faced an incoming winter storm with forecasts of 20–25 centimeters of snow and strong winds. The urgency to complete the repair before the storm highlights how essential skid steers are in rural and agricultural environments. These machines often serve as the primary snow‑clearing equipment for farms, construction yards, and remote properties.
Stories like this illustrate why proper maintenance and accurate reassembly procedures are critical—not just for machine longevity but for day‑to‑day operations.
Practical Advice for Owners of Aging 1845C Machines
As these machines continue to age, owners should consider:
Conclusion
The Case 1845C remains a legendary skid steer loader thanks to its rugged design and dependable hydraulic drive system. However, proper maintenance—especially of the Danfoss OMT wheel motors—is essential to keep these machines performing at their best. Understanding the importance of timing, port alignment, and seal integrity can prevent performance issues such as backward rotation, uneven drive power, or premature component failure.
With careful attention to detail and a solid understanding of the motor’s internal structure, owners can confidently rebuild and maintain these motors, ensuring that their 1845C continues to serve reliably for decades to come.
Owners who maintain these machines today often encounter the need to reseal or rebuild the wheel motors, especially as the machines age past 20 or 30 years. One of the most important but frequently misunderstood aspects of this process is the timing of the wheel motor during reassembly. Improper timing can cause the motor to run backward or operate inefficiently, even if the machine appears functional. This issue was highlighted when a technician discovered misaligned internal ports and blown O‑rings during a reseal job.
The following article explains the design of the wheel motors, the importance of timing, common symptoms of misalignment, and practical guidance for owners and mechanics.
Background of the Case 1845C and Its Hydraulic Drive System
The Case 1845C uses a hydrostatic drive system, meaning each wheel is powered by hydraulic motors rather than mechanical axles. This design allows for zero‑radius turning, high torque at low speeds, and simplified drivetrain maintenance.
Key characteristics of the 1845C drive system include:
- Four independent hydraulic wheel motors
- Chain‑case drive connecting each motor to the wheels
- High‑flow hydraulic pump delivering power to the motors
- Danfoss OMT‑series motors in later production years
This design is known for high torque output, smooth operation, and long service life. However, it requires precise internal alignment during reassembly.
Why Timing Matters in Danfoss OMT Wheel Motors
During a rebuild, the motor must be reassembled so that the rotor, gerotor set, and port plate are aligned correctly. If these components are out of time, the hydraulic flow will not match the intended rotation direction.
Consequences of incorrect timing include:
- The motor may rotate backward
- One side of the machine may lag behind the other
- The machine may drift or pull to one side
- Hydraulic efficiency may drop
- Excess heat or premature seal failure may occur
Common Symptoms of Wheel Motor Seal Failure
As these machines age, seal kits become a routine maintenance item. Symptoms of failing seals include:
- Hydraulic oil leaking into the chain case
- Reduced drive power
- Wheel hesitation or jerking
- Excessive noise from the motor
- Visible oil seepage around the motor housing
Understanding the Port Alignment Issue
Inside the OMT motor, several ports and channels direct hydraulic fluid through the rotor assembly. These ports must align perfectly with the corresponding openings in the housing.
If the ports are misaligned:
- Hydraulic flow becomes restricted
- The motor may run in reverse
- Internal pressure spikes can blow O‑rings
- The machine may behave unpredictably
Recommended Steps for Proper Wheel Motor Timing
Although specific service manuals provide exact diagrams, the general principles of timing a gerotor motor include:
- Ensuring the rotor spline aligns with the port plate reference mark
- Matching the internal timing marks stamped by the manufacturer
- Verifying that the inlet and outlet ports correspond to the correct rotation direction
- Checking that the gerotor set is seated evenly
- Inspecting all O‑rings and seals for correct placement
- Rotating the assembly by hand to confirm smooth movement
Additional Tips for Successful Reassembly
Owners and mechanics often share practical advice based on years of experience:
- Always clean the housing thoroughly before reassembly
- Use assembly grease to hold seals and O‑rings in place
- Replace any questionable components rather than reusing them
- Compare the left and right motors to identify inconsistencies
- Document the disassembly process with photos
- Test the machine at low throttle after reinstallation
A Brief Look at Danfoss and the OMT Motor Line
Danfoss, founded in Denmark in 1933, has become one of the world’s leading manufacturers of hydraulic components. The OMT series, introduced decades ago, is widely used in agricultural, construction, and industrial machinery.
Key advantages of the OMT 250 motor include:
- High torque output
- Long service life
- Modular design for easy servicing
- Compatibility with multiple hydraulic systems
A Real‑World Example of Weather‑Driven Urgency
In one instance, a technician working on a wheel motor rebuild faced an incoming winter storm with forecasts of 20–25 centimeters of snow and strong winds. The urgency to complete the repair before the storm highlights how essential skid steers are in rural and agricultural environments. These machines often serve as the primary snow‑clearing equipment for farms, construction yards, and remote properties.
Stories like this illustrate why proper maintenance and accurate reassembly procedures are critical—not just for machine longevity but for day‑to‑day operations.
Practical Advice for Owners of Aging 1845C Machines
As these machines continue to age, owners should consider:
- Performing proactive seal replacements every 1,500–2,000 hours
- Monitoring hydraulic oil quality and temperature
- Inspecting chain cases for contamination
- Keeping spare seal kits on hand
- Learning the basics of wheel motor timing
Conclusion
The Case 1845C remains a legendary skid steer loader thanks to its rugged design and dependable hydraulic drive system. However, proper maintenance—especially of the Danfoss OMT wheel motors—is essential to keep these machines performing at their best. Understanding the importance of timing, port alignment, and seal integrity can prevent performance issues such as backward rotation, uneven drive power, or premature component failure.
With careful attention to detail and a solid understanding of the motor’s internal structure, owners can confidently rebuild and maintain these motors, ensuring that their 1845C continues to serve reliably for decades to come.
