10-22-2025, 07:32 PM
Bobcat T595 Compact Track Loader Overview
The Bobcat T595 is a mid-frame compact track loader introduced in the late 2010s, designed for grading, lifting, and material handling in tight spaces. With a rated operating capacity of 2,200 pounds and a turbocharged diesel engine producing around 70 horsepower, the T595 combines maneuverability with hydraulic power. Bobcat, founded in 1947, has sold hundreds of thousands of loaders globally, and the T595 remains popular in landscaping, construction, and agricultural fleets.
The T595 features a closed-center hydraulic system with load-sensing capabilities, allowing simultaneous operation of multiple functions. However, under certain conditions, operators may observe unexpected behavior—such as lift arm drift—when performing combined hydraulic actions.
Terminology Notes
Operators report that when lifting the arms and closing the grapple simultaneously—especially with a heavy load—the arms drift downward, sometimes rapidly. When each function is used independently, the system performs normally. System pressure at the quick couplers reads 3,500 psi, and both the load check valve and main relief valve have been inspected with no apparent issues.
This behavior suggests a dynamic interaction between hydraulic circuits rather than a simple mechanical fault.
Possible Causes and Diagnostic Strategy
In Georgia, an operator noticed that his T595’s arms dropped only when closing the grapple with a full load of logs. After checking all external valves, he discovered that the lift cylinders had internal scoring. Replacing the seals resolved the issue. In Montana, a fleet manager traced similar behavior to a worn spool in the control valve block, which allowed cross-flow between circuits under load.
Recommendations for Technicians and Owners
Lift cylinder drift on the Bobcat T595 during simultaneous grapple closure is likely caused by internal leakage or circuit interaction rather than a single failed component. With methodical diagnostics—starting from cylinder seals and valve block behavior—this issue can be resolved without major component replacement. Understanding how hydraulic priority and pressure balance affect multi-function operation is key to maintaining performance and safety.
The Bobcat T595 is a mid-frame compact track loader introduced in the late 2010s, designed for grading, lifting, and material handling in tight spaces. With a rated operating capacity of 2,200 pounds and a turbocharged diesel engine producing around 70 horsepower, the T595 combines maneuverability with hydraulic power. Bobcat, founded in 1947, has sold hundreds of thousands of loaders globally, and the T595 remains popular in landscaping, construction, and agricultural fleets.
The T595 features a closed-center hydraulic system with load-sensing capabilities, allowing simultaneous operation of multiple functions. However, under certain conditions, operators may observe unexpected behavior—such as lift arm drift—when performing combined hydraulic actions.
Terminology Notes
- Lift Cylinder Drift: Unintended lowering of the loader arms due to internal or external hydraulic leakage.
- Load Check Valve: A valve that prevents hydraulic fluid from flowing backward through the cylinder circuit.
- Main Pressure Relief Valve: A safety valve that limits system pressure to prevent damage.
- Closed-Center System: A hydraulic configuration where fluid flow is blocked until a function is activated.
Operators report that when lifting the arms and closing the grapple simultaneously—especially with a heavy load—the arms drift downward, sometimes rapidly. When each function is used independently, the system performs normally. System pressure at the quick couplers reads 3,500 psi, and both the load check valve and main relief valve have been inspected with no apparent issues.
This behavior suggests a dynamic interaction between hydraulic circuits rather than a simple mechanical fault.
Possible Causes and Diagnostic Strategy
- Hydraulic Priority Conflict
In closed-center systems, simultaneous commands can cause pressure drops if one circuit is prioritized. If the grapple circuit draws flow aggressively, the lift circuit may lose pressure momentarily, causing drift.
- Internal Cylinder Leakage
Even if the load check valve is intact, worn seals inside the lift cylinders can allow fluid to bypass the piston, especially under combined load.
- Valve Block Cross-Talk
The control valve block may have internal leakage paths or spool overlap that allow unintended flow between circuits.
- Relief Valve Lag or Flutter
Under rapid command changes, the relief valve may momentarily open or fail to maintain pressure, especially if contaminated or worn.
- Grapple Cylinder Backpressure
If the grapple cylinder generates backpressure during closure, it may push fluid into the lift circuit, causing instability.
In Georgia, an operator noticed that his T595’s arms dropped only when closing the grapple with a full load of logs. After checking all external valves, he discovered that the lift cylinders had internal scoring. Replacing the seals resolved the issue. In Montana, a fleet manager traced similar behavior to a worn spool in the control valve block, which allowed cross-flow between circuits under load.
Recommendations for Technicians and Owners
- Test Cylinder Integrity: Disconnect and cap the lift cylinder ports, then apply pressure to check for drift.
- Inspect Valve Block for Wear: Look for spool scoring or contamination that may cause cross-leakage.
- Monitor Pressure During Combined Functions: Use gauges on both circuits to detect pressure drops or spikes.
- Replace Seals Proactively: If the machine has over 2,000 hours, consider resealing lift cylinders.
- Clean and Recalibrate Relief Valves: Ensure consistent pressure regulation under dynamic loads.
Lift cylinder drift on the Bobcat T595 during simultaneous grapple closure is likely caused by internal leakage or circuit interaction rather than a single failed component. With methodical diagnostics—starting from cylinder seals and valve block behavior—this issue can be resolved without major component replacement. Understanding how hydraulic priority and pressure balance affect multi-function operation is key to maintaining performance and safety.
