10-18-2025, 01:53 PM
Legacy of the Case 1845C Skid Steer
The Case 1845C skid steer loader, introduced in the late 1980s, became one of the most iconic and widely used compact loaders in North America and Europe. Manufactured by Case Corporation—now part of CNH Industrial—the 1845C was known for its rugged design, hydrostatic drive system, and versatility across construction, agriculture, and landscaping. With over 60,000 units sold globally, it remains a staple on job sites and farms, even decades after production ceased.
The machine features a tandem hydraulic drive pump system, which powers both drive motors independently. This configuration allows for precise maneuvering and high torque output, especially in confined spaces. However, as these machines age, hydraulic issues—particularly involving the tandem pump—become increasingly common.
Understanding the Tandem Drive Pump System
In one documented case, a rebuilt tandem pump began leaking after only five hours of operation. The drive shaft seal was pushed out, indicating excessive internal pressure. The operator had previously used incorrect hydraulic oil, which may have contributed to premature wear. Upon inspection, the mechanic suspected a return flow restriction.
Key contributing factors included:
To restore and protect the tandem pump system, the following steps are advised:
One Austrian operator spent over $3,000 on a pump rebuild, only to face seal failure within days. The oversight of not priming the pump and using incompatible oil led to costly downtime. In another case from Wisconsin, a contractor discovered that a non-OEM filter caused subtle flow restrictions, eventually damaging the pump. After switching to the recommended filter and oil, the machine ran flawlessly for years.
Service Manual and Technical Support
Access to a detailed service manual is crucial for proper maintenance. It includes:
Conclusion
The Case 1845C remains a workhorse in the field, but its tandem drive pump demands careful attention. Using the correct oil, filters, and installation procedures can prevent premature failure and extend the life of this legendary machine. As parts age and aftermarket replacements proliferate, compatibility and precision become more important than ever. With proper care, the 1845C can continue serving for decades to come.
The Case 1845C skid steer loader, introduced in the late 1980s, became one of the most iconic and widely used compact loaders in North America and Europe. Manufactured by Case Corporation—now part of CNH Industrial—the 1845C was known for its rugged design, hydrostatic drive system, and versatility across construction, agriculture, and landscaping. With over 60,000 units sold globally, it remains a staple on job sites and farms, even decades after production ceased.
The machine features a tandem hydraulic drive pump system, which powers both drive motors independently. This configuration allows for precise maneuvering and high torque output, especially in confined spaces. However, as these machines age, hydraulic issues—particularly involving the tandem pump—become increasingly common.
Understanding the Tandem Drive Pump System
- Tandem Pump: A dual-section hydraulic pump that supplies fluid to two separate circuits, typically the left and right drive motors.
- Case Drain Line: A low-pressure return line that allows excess fluid and leakage from the pump and motors to flow back to the reservoir.
- Return Filter: A filtration unit that cleans hydraulic fluid before it re-enters the tank. A clogged filter can cause backpressure and seal failure.
- Seal Ring: A rubber or composite ring that prevents fluid leakage along the pump shaft. Excess pressure can dislodge it.
In one documented case, a rebuilt tandem pump began leaking after only five hours of operation. The drive shaft seal was pushed out, indicating excessive internal pressure. The operator had previously used incorrect hydraulic oil, which may have contributed to premature wear. Upon inspection, the mechanic suspected a return flow restriction.
Key contributing factors included:
- Clogged Return Filter: A blocked filter can cause pressure buildup in the case drain line, forcing seals to fail.
- Unprimed Pump: Installing a pump without pre-filling it with oil can lead to cavitation, damaging internal components.
- Non-OEM Drive Motor: A replacement motor on the left side may have been incompatible with the system’s flow characteristics.
- Incorrect Oil Type: Using standard hydraulic oil instead of the recommended 10W-30 motor oil with HTO additive can degrade hydrostatic components.
- HTO Additive: A proprietary friction modifier used in Case hydrostatic systems to reduce wear and improve lubrication.
- Cavitation: The formation of vapor bubbles in hydraulic fluid due to low pressure, which collapse and damage internal surfaces.
- Hydrostatic Drive: A propulsion system using hydraulic fluid to power motors directly, offering smooth and variable speed control.
To restore and protect the tandem pump system, the following steps are advised:
- Replace the return filter with an OEM-compatible unit (e.g., Donaldson or Mann) and verify flow direction.
- Install a pressure gauge at the filter housing to monitor backpressure during operation.
- Prime the pump before installation by filling it with clean oil through the inlet port.
- Flush the hydraulic system using a service manual-guided procedure, removing contaminants and old fluid.
- Reinstall the original drive motor if compatibility issues are suspected.
- Use Case-approved 10W-30 motor oil with HTO additive at a ratio of 1 liter per 5 gallons, or purchase HTO-premix for convenience.
One Austrian operator spent over $3,000 on a pump rebuild, only to face seal failure within days. The oversight of not priming the pump and using incompatible oil led to costly downtime. In another case from Wisconsin, a contractor discovered that a non-OEM filter caused subtle flow restrictions, eventually damaging the pump. After switching to the recommended filter and oil, the machine ran flawlessly for years.
Service Manual and Technical Support
Access to a detailed service manual is crucial for proper maintenance. It includes:
- Hydraulic schematics
- Priming procedures
- System flushing instructions
- Torque specifications for pump mounting
Conclusion
The Case 1845C remains a workhorse in the field, but its tandem drive pump demands careful attention. Using the correct oil, filters, and installation procedures can prevent premature failure and extend the life of this legendary machine. As parts age and aftermarket replacements proliferate, compatibility and precision become more important than ever. With proper care, the 1845C can continue serving for decades to come.
