How to Lower Arms When Aux Hydraulics Are Engaged on Case 90XT: A Practical Guide

[MikePhua]

The Case 90XT is a versatile compact track loader known for its impressive lifting and digging capabilities. Like many machines of its class, the 90XT has auxiliary hydraulics that provide power to various attachments such as augers, grapples, and other hydraulic-powered tools. However, many operators encounter a common problem: lowering the arms while the auxiliary hydraulics are engaged.
This article explores the issue and provides solutions for operators looking to safely lower the arms while the auxiliary hydraulics are still active.
Understanding the Case 90XT Hydraulic System
The Case 90XT is equipped with a hydraulic system that powers both the primary lift arms and auxiliary tools. The lift arms and auxiliary hydraulics are controlled separately, but both are powered by the same hydraulic fluid reservoir.
In a typical hydraulic system, the fluid is pumped by the hydraulic pump and directed through control valves to perform specific tasks. The auxiliary hydraulic system controls tools like augers, pallet forks, or trenchers, while the lift arms are designed to raise and lower the bucket or other attachments.
Problem Description: Lowering the Arms with Aux Hydraulics Engaged
One of the challenges that operators often face is lowering the arms while the auxiliary hydraulics are engaged. Typically, when auxiliary hydraulics are engaged, the system prioritizes the flow of hydraulic fluid to the attachment, and this may restrict or lock the lift arms in place. This issue arises because the hydraulic control valve prioritizes the auxiliary flow, making it difficult to control the lift arms independently.
Causes of the Problem
There are several factors that can contribute to the inability to lower the arms when auxiliary hydraulics are engaged:
1. Priority Flow to Aux Hydraulics
On many machines, including the Case 90XT, the auxiliary hydraulics have a priority over the lift arm system. This means that when the auxiliary hydraulics are activated, the hydraulic fluid is directed to the attachment, reducing or cutting off flow to the arms. As a result, the lift arms may become unresponsive or stuck in a raised position.
2. Hydraulic Control Valve Configuration
The hydraulic control valve configuration may also contribute to this issue. On some machines, the valve prioritizes certain hydraulic functions, such as auxiliary hydraulics, before allowing the lift arm control to function properly. This issue is often more noticeable when the auxiliary hydraulics are used in combination with other functions.
3. Hydraulic Pressure Build-up
When the auxiliary hydraulics are engaged, pressure is generated within the system. This pressure build-up can sometimes make it harder for the lift arms to lower, as the hydraulic system might not be able to release pressure quickly enough.
Solution 1: Deactivate Aux Hydraulics Temporarily
The simplest solution to this problem is to momentarily deactivate the auxiliary hydraulics before attempting to lower the arms. This will allow the hydraulic system to redirect fluid flow to the lift arms, enabling them to function properly.
To do this:

• Release the Auxiliary Function: If you're using an attachment, disengage the auxiliary hydraulic controls by turning off or retracting the hydraulic flow to the attachment.
  
• Lower the Arms: With the auxiliary hydraulics off, use the control to lower the arms as you normally would.
  
• Re-engage the Auxiliary Hydraulics: Once the arms are lowered to the desired position, you can re-engage the auxiliary hydraulics to resume work with the attachment.
  

This solution works well in most cases, but it does require the operator to be aware of the situation and may cause downtime if the attachment needs to be re-engaged frequently.
Solution 2: Use an Auxiliary Hydraulic Flow Restrictor Valve
If you need to keep the auxiliary hydraulics engaged while lowering the arms, a flow restrictor valve can be installed to limit the flow to the attachment. The restrictor valve essentially creates a restriction in the flow of hydraulic fluid to the attachment, allowing enough pressure to build in the arm control system to lower the arms.

• Install a Flow Restrictor Valve: Many hydraulic systems have ports that can accommodate a flow restrictor valve. Install the valve in-line with the auxiliary hydraulic lines to regulate fluid flow.
  
• Adjust the Valve: The restrictor valve should be adjusted to a level where the auxiliary hydraulics can still function, but enough hydraulic pressure is available to lower the arms.
  

This solution is often used when the operator frequently works with attachments and needs to ensure both functions can operate simultaneously.
Solution 3: Use a Hydraulic Flow Divider
Another option for keeping the arms and auxiliary hydraulics working at the same time is installing a hydraulic flow divider. A flow divider splits the hydraulic flow into two separate streams, one for the arms and one for the attachment. This ensures that the hydraulic fluid is evenly distributed between both systems, allowing them to work together.

• Install a Flow Divider: A hydraulic flow divider can be integrated into the hydraulic system of the machine.
  
• Adjust the Flow Split: The flow divider allows you to control the proportion of fluid that goes to each system. By adjusting the flow split, you can ensure that the arms and the attachment receive sufficient hydraulic pressure for their respective tasks.
  

This solution is often more expensive but is ideal for those who need to operate both systems simultaneously without compromising performance.
Solution 4: Consult the Operator’s Manual
If you are unsure about the specific configuration of your Case 90XT, it’s always a good idea to consult the operator’s manual. The manual often provides valuable information about the hydraulic system, including how to configure it for optimal performance and how to troubleshoot common issues like this one.

• Check Hydraulic System Diagrams: The manual often includes hydraulic schematics that show how the fluid flows through the system, helping you understand where the priority flow is directed.
  
• Follow Manufacturer Recommendations: The manual may also offer guidance on which valves, restrictors, or components can be added or adjusted to resolve the issue.
  

Conclusion
Lowering the arms while the auxiliary hydraulics are engaged on the Case 90XT can be challenging due to the way hydraulic fluid is prioritized in the system. By deactivating the auxiliary hydraulics temporarily, using a flow restrictor valve or flow divider, and consulting the operator’s manual, operators can successfully address this issue and improve the efficiency of their machines. With the right understanding of the hydraulic system and these simple solutions, operators can get the most out of their Case 90XT, making it a more versatile and effective tool for a wide range of tasks.