08-20-2025, 05:42 PM
The Tigercat 620E is a powerful industrial skidder widely used in forestry operations. However, some users have experienced transmission difficulties, particularly related to the electronic control valve, that can lead to shifts problems and eventual transmission failure.
Common Transmission Problems
Transmission issues in the Tigercat 620E often stem from electronic valve problems that disrupt clutch control, leading to shifting malfunctions and potential failure. Operators facing these problems have options ranging from manual conversions to preventive maintenance measures. Understanding the system and choosing machines or configurations accordingly can enhance reliability and reduce downtime in demanding forestry work.
Common Transmission Problems
- Shifting issues such as delayed slips or harsh gear changes can develop after several thousand hours of operation.
- Electronic control valve malfunctions interfere with clutch engagement, causing early wear or burnout of clutch packs.
- The Efficient High Speed (EHS) hydrostatic system designed to optimize tractive effort has been reported to cause unintended automatic high-speed shifts under heavy loads, stressing components.
- Some operators have seen transmissions quit completely after experiencing initial shifting faults.
- The main root cause is often electronic control valve failure within the transmission system, affecting hydraulic pressures that regulate clutch operation.
- Increased resistance from modifications like towing heavy implements or operating on rough terrain can exacerbate transmission stress.
- Some reports indicate that Tigercat dealers discontinued ordering EHS-equipped 620E models due to persistent problems.
- Owners may choose to convert the transmission control from electronic to manual or mechanical valves, eliminating electronic failure points but changing maintenance and operational dynamics.
- Regular transmission fluid changes and proper bleeding are essential preventative measures.
- Checking and maintaining drive belt tension ensures adequate power transmission to the hydrostatic system.
- Replacing worn or weak springs within the transmission can restore clutch engagement force and reduce slipping.
- Seal replacements on charge pumps inside the transmission may address leaks and loss of hydraulic pressure.
- Many users prefer models without electronic transmission controls to avoid complex failures and simplify maintenance.
- The 620E with EHS system tends to encounter issues around 2,000 hours of use, while non-EHS models show longer transmission life.
- Some operators recommend upgrading to newer models like the Tigercat 632E for improved transmission reliability.
- Electronic Control Valve: A valve controlling hydraulic pressure digitally to manage transmission shifts.
- Clutch Pack: A component in the transmission engaging gears by friction.
- Hydrostatic System: A transmission system using hydraulic fluid pressure to transfer power and control speed.
- Efficient High Speed (EHS): A hydrostatic drive feature that boosts tractive effort during heavy loads and optimizes speed on level terrain.
- Charge Pump: A pump delivering hydraulic fluid under pressure inside the transmission to support clutch function.
Transmission issues in the Tigercat 620E often stem from electronic valve problems that disrupt clutch control, leading to shifting malfunctions and potential failure. Operators facing these problems have options ranging from manual conversions to preventive maintenance measures. Understanding the system and choosing machines or configurations accordingly can enhance reliability and reduce downtime in demanding forestry work.
