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The Legacy of the Case 1845C
The Case 1845C skid steer loader, introduced in the early 1990s by Case Corporation, became one of the most iconic and widely used compact loaders in North America. With over 60,000 units sold during its production run, the 1845C earned a reputation for reliability, simplicity, and ease of maintenance. Case, founded in 1842 by Jerome Increase Case, had long been a pioneer in agricultural and construction machinery. By the time the 1845C was released, Case had already merged with International Harvester to form Case IH, and later became part of CNH Industrial.
The 1845C featured a 51-horsepower Cummins diesel engine, hydrostatic drive, and a rated operating capacity of around 1,700 pounds. Its popularity stemmed from its robust design, mechanical simplicity, and the ability to operate in harsh conditions with minimal downtime. However, like any machine, age and wear can reveal vulnerabilities—especially in its hydrostatic transmission system.
Symptoms of Drive Loss When Warm
One of the more perplexing issues reported by operators is the loss of drive power on both sides of the 1845C when the machine warms up. Curiously, the loader regains mobility when the bucket is lowered. This behavior suggests a complex interplay between hydraulic pressure, thermal expansion, and internal component wear.
The machine typically starts strong when cold, but as hydraulic fluid heats and viscosity drops, drive response diminishes. Raising the bucket has no effect, but lowering it seems to temporarily restore motion. This anomaly points toward a charge pressure deficiency in the hydrostatic system.
Understanding Charge Pressure and the Tandem Pump
In hydrostatic systems, “charge pressure” refers to the low-pressure supply that feeds the high-pressure loop of the hydrostatic pump. It ensures that the pump is never starved of fluid and helps lubricate internal components. The Case 1845C uses a tandem pump configuration, where the charge pump is nestled between two main drive pumps.
When the bucket is lowered, the hydraulic tank may experience a momentary increase in pressure due to displaced fluid and air compression. This can assist the charge pump by boosting flow slightly—just enough to overcome marginal deficiencies. However, this is not a sustainable solution and indicates that the charge pump is underperforming.
Common Causes of Charge Pressure Failure
Several factors can contribute to low charge pressure in the 1845C:
Testing and Diagnosis
To confirm charge pressure issues, technicians should perform a pressure test at the charge circuit. Normal charge pressure for the 1845C in neutral should be around 250–300 psi. In the reported case, only 160 psi was observed. Attempts to shim the relief valve spring yielded no improvement, confirming internal pump degradation.
Recommended diagnostic steps include:
Replacing or rebuilding the charge pump requires separating the hydrostatic transmission halves—a labor-intensive process. Depending on parts availability and labor rates, costs can range from $1,200 to $3,000. Some operators opt for remanufactured pumps, while others attempt in-house rebuilds using aftermarket kits.
It’s important to note that the 1845C uses a single pump to drive both sides. Therefore, a charge pressure issue affects both drive motors equally. If only one side were weak, the problem would likely reside in the rotating group or motor of that side.
Operator Anecdotes and Lessons Learned
One technician recalled a similar issue on a 1991 model where the machine barely moved and jerked forward intermittently. After replacing the flywheel and inspecting the transmission, they discovered that the charge pump housing had worn unevenly, causing internal leakage. The fix involved machining the housing and replacing the gears—a solution that extended the machine’s life by several years.
In another case, a rental fleet manager noticed that multiple 1845Cs exhibited sluggish drive after prolonged use in dusty environments. The culprit was clogged hydraulic filters and contaminated fluid, which starved the charge pump. Regular maintenance and fluid analysis became standard practice thereafter.
Preventive Measures and Recommendations
To avoid similar failures, operators and fleet managers should consider the following:
The Case 1845C remains a workhorse in the compact loader category, but its hydrostatic system demands attention as the machine ages. Loss of drive when warm, especially when alleviated by lowering the bucket, is a telltale sign of charge pressure deficiency. Through careful diagnosis, component inspection, and preventive maintenance, operators can restore performance and extend the life of this legendary machine.
The Case 1845C skid steer loader, introduced in the early 1990s by Case Corporation, became one of the most iconic and widely used compact loaders in North America. With over 60,000 units sold during its production run, the 1845C earned a reputation for reliability, simplicity, and ease of maintenance. Case, founded in 1842 by Jerome Increase Case, had long been a pioneer in agricultural and construction machinery. By the time the 1845C was released, Case had already merged with International Harvester to form Case IH, and later became part of CNH Industrial.
The 1845C featured a 51-horsepower Cummins diesel engine, hydrostatic drive, and a rated operating capacity of around 1,700 pounds. Its popularity stemmed from its robust design, mechanical simplicity, and the ability to operate in harsh conditions with minimal downtime. However, like any machine, age and wear can reveal vulnerabilities—especially in its hydrostatic transmission system.
Symptoms of Drive Loss When Warm
One of the more perplexing issues reported by operators is the loss of drive power on both sides of the 1845C when the machine warms up. Curiously, the loader regains mobility when the bucket is lowered. This behavior suggests a complex interplay between hydraulic pressure, thermal expansion, and internal component wear.
The machine typically starts strong when cold, but as hydraulic fluid heats and viscosity drops, drive response diminishes. Raising the bucket has no effect, but lowering it seems to temporarily restore motion. This anomaly points toward a charge pressure deficiency in the hydrostatic system.
Understanding Charge Pressure and the Tandem Pump
In hydrostatic systems, “charge pressure” refers to the low-pressure supply that feeds the high-pressure loop of the hydrostatic pump. It ensures that the pump is never starved of fluid and helps lubricate internal components. The Case 1845C uses a tandem pump configuration, where the charge pump is nestled between two main drive pumps.
When the bucket is lowered, the hydraulic tank may experience a momentary increase in pressure due to displaced fluid and air compression. This can assist the charge pump by boosting flow slightly—just enough to overcome marginal deficiencies. However, this is not a sustainable solution and indicates that the charge pump is underperforming.
Common Causes of Charge Pressure Failure
Several factors can contribute to low charge pressure in the 1845C:
- Worn charge pump gears or housing: Over time, internal wear reduces volumetric efficiency.
- Stuck charge pressure relief valve: If the relief valve remains open, pressure bleeds off continuously.
- Misaligned or rotated pump housing: Improper assembly can cause internal bypassing or loss of alignment with the drive shaft.
- Missing or dislodged alignment pin: A small but critical component that ensures proper orientation of the pump housing.
Testing and Diagnosis
To confirm charge pressure issues, technicians should perform a pressure test at the charge circuit. Normal charge pressure for the 1845C in neutral should be around 250–300 psi. In the reported case, only 160 psi was observed. Attempts to shim the relief valve spring yielded no improvement, confirming internal pump degradation.
Recommended diagnostic steps include:
- Installing a pressure gauge at the charge test port
- Checking relief valve operation and spring tension
- Inspecting the tandem pump for wear or misalignment
- Verifying filter and inlet line integrity
Replacing or rebuilding the charge pump requires separating the hydrostatic transmission halves—a labor-intensive process. Depending on parts availability and labor rates, costs can range from $1,200 to $3,000. Some operators opt for remanufactured pumps, while others attempt in-house rebuilds using aftermarket kits.
It’s important to note that the 1845C uses a single pump to drive both sides. Therefore, a charge pressure issue affects both drive motors equally. If only one side were weak, the problem would likely reside in the rotating group or motor of that side.
Operator Anecdotes and Lessons Learned
One technician recalled a similar issue on a 1991 model where the machine barely moved and jerked forward intermittently. After replacing the flywheel and inspecting the transmission, they discovered that the charge pump housing had worn unevenly, causing internal leakage. The fix involved machining the housing and replacing the gears—a solution that extended the machine’s life by several years.
In another case, a rental fleet manager noticed that multiple 1845Cs exhibited sluggish drive after prolonged use in dusty environments. The culprit was clogged hydraulic filters and contaminated fluid, which starved the charge pump. Regular maintenance and fluid analysis became standard practice thereafter.
Preventive Measures and Recommendations
To avoid similar failures, operators and fleet managers should consider the following:
- Replace hydraulic filters every 250 hours
- Use OEM-spec hydraulic fluid with proper viscosity index
- Monitor charge pressure during routine service
- Inspect relief valves and pump alignment annually
- Avoid prolonged idling in high ambient temperatures
The Case 1845C remains a workhorse in the compact loader category, but its hydrostatic system demands attention as the machine ages. Loss of drive when warm, especially when alleviated by lowering the bucket, is a telltale sign of charge pressure deficiency. Through careful diagnosis, component inspection, and preventive maintenance, operators can restore performance and extend the life of this legendary machine.
