Identifying and Replacing the Tandem Pump in a Case 1840 Skid Steer

[MikePhua]

The Case 1840 is a reliable and durable skid steer loader that has served many construction and landscaping professionals over the years. However, like all machines, it requires maintenance and occasional part replacements to keep it running smoothly. One key component that may need attention is the tandem hydraulic pump, which plays a crucial role in powering the loader’s various functions.
In this article, we will explore the purpose and function of the tandem pump in a Case 1840 skid steer, how to identify potential issues with the pump, and the steps for replacing or repairing it. We’ll also provide additional tips on maintenance to ensure the longevity and efficiency of the hydraulic system.
What is a Tandem Hydraulic Pump?
A tandem hydraulic pump is a specific type of pump used in heavy equipment like the Case 1840 skid steer. Unlike a single-stage pump, which only provides hydraulic pressure for one system, a tandem pump combines multiple pumps into a single unit to provide hydraulic power to several systems at once. In the Case 1840, this means the tandem pump supplies power to both the drive motor and the auxiliary hydraulic system, enabling various functions such as lifting, tilting, and powering attachments.
The tandem pump consists of:

• Two Separate Pumps: One pump powers the drive system (which moves the skid steer) while the other powers auxiliary functions (such as the boom and bucket).
  
• Common Drive Shaft: Both pumps share a common drive shaft, allowing them to operate simultaneously, but independently of each other.
  
• Shared Fluid Reservoir: The tandem pump uses hydraulic fluid from the same reservoir, ensuring that both systems are adequately lubricated and powered.
  

Common Issues with the Tandem Pump in the Case 1840
Over time, the tandem pump in the Case 1840 can experience wear or failure due to high-pressure conditions, contamination, or improper maintenance. Common symptoms of a failing tandem pump include:

1. Slow or Weak Hydraulic Functions
   When the tandem pump is not providing enough pressure to the system, the loader may exhibit weak or sluggish movements, such as slow bucket lifting, slower wheel movements, or failure to operate auxiliary attachments.
   • Possible Causes:
     • Wear in the pump’s internal components, such as bearings, gears, or seals, leading to decreased hydraulic pressure.
       
     • Contaminants in the hydraulic fluid, which can clog the pump and reduce its efficiency.
       
     • Air entering the hydraulic system, causing cavitation, which results in the pump failing to generate enough pressure.
       
2. Excessive Noise or Vibration
   If the tandem pump is damaged or worn, it may produce unusual noises or vibrations. This can manifest as a whining sound, grinding, or pulsing, particularly when operating the machine under load.
   • Possible Causes:
     • Cavitation, which occurs when air pockets form in the hydraulic fluid due to low fluid levels or pump failure.
       
     • Mechanical wear or damage to the internal components of the pump, such as the drive shaft or gears.
       
3. Hydraulic Fluid Leaks
   Leaking hydraulic fluid around the tandem pump or its connections is a clear sign that there is a problem. Leaks may occur due to worn seals, gaskets, or cracks in the pump housing.
   • Possible Causes:
     • Worn seals or gaskets that no longer provide a proper seal, leading to fluid leakage.
       
     • Cracks or damage to the pump housing caused by excessive pressure or physical impact.
       
4. Erratic Functioning of Attachments
   When the tandem pump is not functioning correctly, the loader may experience erratic behavior when operating attachments, such as boom movement hesitation or inconsistent bucket tilt.
   • Possible Causes:
     • Inconsistent hydraulic flow due to internal wear or contamination in the pump.
       
     • A damaged drive motor affecting the overall hydraulic power being distributed to the system.
       

Diagnosing Tandem Pump Problems in the Case 1840
To identify issues with the tandem pump, operators should perform a series of checks to diagnose the problem:

1. Check Hydraulic Fluid Levels
   Ensure that the hydraulic fluid is at the correct level and is clean. Low or contaminated fluid can cause the tandem pump to fail by not providing sufficient lubrication and pressure to the system.
   • If the fluid is low, top it up using the recommended type of hydraulic fluid.
     
   • If the fluid is contaminated or dirty, drain and replace it, ensuring that the fluid meets the specifications outlined in the operator’s manual.
     
2. Listen for Unusual Noises
   Operate the skid steer and listen for any unusual sounds, such as whining, grinding, or excessive vibration, which could indicate a problem with the tandem pump. If these sounds are present, the pump may need to be inspected and possibly replaced.
   
3. Check for Hydraulic Leaks
   Inspect the area around the tandem pump for hydraulic fluid leaks. Leaking fluid can not only reduce the system’s efficiency but also lead to further damage to the pump and surrounding components.
   • Inspect hoses, fittings, and the pump itself for signs of leaks.
     
   • Tighten or replace any loose fittings, and replace worn seals or gaskets as needed.
     
4. Test Hydraulic Pressure
   Using a hydraulic pressure gauge, check the output pressure of the tandem pump. Compare the readings to the manufacturer’s specifications. If the pressure is low or inconsistent, the pump may be failing.
   • A professional technician may be required to perform this test accurately, as it involves accessing the hydraulic system’s pressure points.
     

Replacing the Tandem Pump in the Case 1840
If the tandem pump is diagnosed as faulty and requires replacement, the process can be challenging but manageable with the right tools and knowledge. Below is a general outline of the steps involved:

1. Prepare the Machine
   • Turn off the engine and disconnect the battery to avoid any electrical hazards.
     
   • Lift the machine using the jack stands or hydraulic lift to provide adequate access to the tandem pump.
     
2. Drain the Hydraulic System
   • Drain the hydraulic fluid from the system into a proper disposal container.
     
   • Remove any panels or covers blocking access to the pump.
     
3. Disconnect the Hydraulic Lines
   • Using the appropriate wrenches, disconnect the hydraulic lines connected to the tandem pump. Be prepared for residual fluid to leak from the lines.
     
4. Remove the Tandem Pump
   • Loosen the mounting bolts securing the pump to the frame.
     
   • Remove the pump and any associated components, such as the drive shaft or seals.
     
5. Install the New Tandem Pump
   • Position the new tandem pump into place, ensuring that it aligns with the mounting holes and connections.
     
   • Reinstall the drive shaft, hydraulic lines, and any seals or gaskets.
     
   • Tighten all bolts securely to ensure proper installation.
     
6. Refill and Bleed the Hydraulic System
   • Refill the hydraulic reservoir with fresh, clean hydraulic fluid.
     
   • Bleed the hydraulic system to remove any air pockets and ensure the system operates smoothly.
     
7. Test the New Pump
   • Start the machine and test all hydraulic functions to ensure that the new tandem pump is working properly.
     
   • Check for leaks, unusual noises, or pressure issues, and address them if necessary.
     

Preventative Maintenance for the Hydraulic System
To avoid future tandem pump failures and extend the life of the hydraulic system in your Case 1840, follow these preventive maintenance tips:

1. Regular Fluid Checks
   • Always maintain proper fluid levels and keep the hydraulic fluid clean. Change the fluid at the recommended intervals.
     
2. Inspect for Leaks
   • Regularly inspect hydraulic hoses, fittings, and the pump for signs of leaks or wear. Tighten any loose fittings and replace damaged hoses as needed.
     
3. Clean the Hydraulic System
   • Keep the hydraulic cooler and filter clean to prevent contamination from entering the system.
     
4. Monitor Pump Pressure
   • Periodically check the hydraulic pressure to ensure the system is functioning optimally.
     

Conclusion
The tandem pump in the Case 1840 skid steer plays a vital role in the performance of the machine, powering both the drive system and auxiliary hydraulic functions. Issues such as slow or weak hydraulic functions, excessive noise, or fluid leaks are all signs that the tandem pump may require attention. By following proper diagnostic steps and performing routine maintenance, operators can extend the life of the pump and keep their machine running at peak performance. If replacement is necessary, it is important to follow the correct procedures to ensure a successful repair.