The Massey Ferguson 135 tractor is a true workhorse, revered by farmers and enthusiasts for its reliability and robust design. Central to its operation is the clutch system, a critical component that enables seamless power transfer and gear changes. Over time, like any mechanical part, the clutch can experience wear or misalignment, leading to issues such as slipping, hard shifting, or difficulty engaging the power take-off (PTO). Properly adjusting the clutch is not just about resolving immediate problems; it’s essential for maintaining the tractor’s efficiency, prolonging the lifespan of the clutch assembly, and ensuring safe operation. This guide will walk you through the necessary steps to understand, diagnose, and precisely adjust the clutch on your Massey Ferguson 135, restoring its smooth performance and keeping your venerable machine running optimally.
Understanding your Massey Ferguson 135 clutch system
Before diving into adjustments, it is vital to grasp the basics of your MF 135’s clutch mechanism. This tractor typically employs a dual-stage clutch, a sophisticated design that separates power to the transmission and the power take-off (PTO) independently. When you press the clutch pedal, the first stage disengages the main drive to the wheels, allowing you to shift gears. Pushing the pedal further activates the second stage, which disengages the PTO drive. This dual functionality is incredibly useful, enabling you to stop the tractor’s forward motion while still operating PTO-driven implements like mowers or tillers. The system consists of a pressure plate, clutch disc, release bearing, and a set of release fingers (or levers) which apply pressure to the clutch disc. Misalignment or wear in any of these components, particularly the release fingers, can throw the entire system out of calibration, making proper adjustment crucial for optimal operation of both the main drive and the PTO.
Identifying common clutch problems and why adjustment is key
Recognizing the symptoms of a poorly adjusted clutch is the first step toward a solution. Common indicators include the clutch slipping, where the engine revs but the tractor does not accelerate proportionately, especially under load. Another frequent complaint is difficulty shifting gears, often accompanied by grinding noises, which suggests the main drive clutch is not fully disengaging. For the PTO, you might experience issues engaging or disengaging implements smoothly, or the PTO might continue to spin even when the pedal is fully depressed, indicating that the second stage is not working correctly. These problems not only impede work efficiency but also accelerate wear on the transmission components and the clutch itself, potentially leading to costly repairs. A correctly adjusted clutch ensures that the pressure plate applies and releases pressure evenly across the clutch disc, maximizing its lifespan and providing smooth, precise control over the tractor’s power output.
Step-by-step guide to adjusting the clutch free play
Adjusting the clutch on your Massey Ferguson 135 involves setting the correct “free play” at the pedal and ensuring the internal release fingers are evenly calibrated. Always begin with safety: ensure the tractor is on level ground, the engine is off, and the wheels are chocked to prevent any movement. The first step is to check the pedal free play. You should have approximately 1 inch (25mm) of free play at the top of the pedal before you feel resistance, corresponding to the initial engagement of the main drive clutch. This can be adjusted by loosening the lock nut on the clutch pedal linkage rod and turning the adjusting nut until the desired free play is achieved, then re-tightening the lock nut.
For the internal adjustment of the main clutch release fingers and the PTO clutch, you’ll need to remove the inspection cover located at the bottom of the bell housing, usually just beneath the engine and transmission junction. With the cover removed, you’ll see three adjusting screws (fingers) that press against the release bearing. These fingers need to be set evenly to ensure the main clutch disengages smoothly. Carefully rotate the engine by hand (or by bumping the starter with the ignition off) to bring each finger into view. Using a feeler gauge, ensure there is an equal gap (typically around 0.080-0.090 inches or 2.0-2.3mm, consult your specific service manual for exact specifications) between the tip of each release finger and the release bearing when the clutch is engaged. Adjust these screws incrementally until all three gaps are uniform. For the PTO clutch, which engages deeper in the pedal travel, there are usually separate adjustment points, often in the form of nuts on studs accessible through the same inspection plate. These adjust the throw-out for the PTO plate. The goal here is to ensure the PTO fully disengages when the pedal is pressed to its second stage. Again, refer to your service manual for precise measurements, but a common setting involves a small clearance between the PTO throw-out levers and the PTO clutch plate.
Here’s a quick reference for common clutch settings:
| Adjustment Point | Typical Specification | Measurement Unit |
|---|---|---|
| Clutch Pedal Free Play (Main Drive) | 1.0 – 1.25 | inch (in) |
| Main Clutch Release Finger Gap | 0.080 – 0.090 | inch (in) |
| PTO Clutch Engagement Point (relative to pedal travel) | Deeper than main drive | N/A |
Note: Always consult your specific Massey Ferguson 135 service manual for precise and accurate specifications, as minor variations can occur between models and years.
Fine-tuning and testing for optimal performance
After completing the adjustments, the crucial next step is to test the clutch thoroughly to ensure optimal performance. Start the tractor in a safe, open area. Engage and disengage the main drive clutch several times, paying close attention to the smoothness of engagement and disengagement. There should be no slipping, grabbing, or grinding during gear changes. Next, test the PTO. Engage a PTO-driven implement (if safe to do so and conditions permit) or simply engage the PTO with the tractor stationary. Observe if it engages smoothly and disengages completely when the pedal is pressed fully. If you notice any issues – persistent slipping, difficulty shifting, or the PTO still spinning – it indicates that further fine-tuning is required. Revisit the adjustment points, making small, incremental changes until the operation feels precise and reliable. If, despite repeated adjustments, problems persist, it may signal that the clutch components themselves are worn beyond adjustment and require replacement. In such cases, or if you feel uncomfortable performing these detailed adjustments, seeking assistance from a qualified agricultural mechanic is always a wise decision to prevent further damage.
Adjusting the clutch on your Massey Ferguson 135 is a fundamental maintenance task that significantly impacts your tractor’s operational efficiency and longevity. We’ve explored the dual-stage clutch system, pinpointed common issues like slipping and hard shifting, and provided a detailed, step-by-step guide for precise adjustment of both the pedal free play and the internal release fingers. Understanding these mechanisms and patiently following the adjustment procedures will ensure your main drive and PTO operate smoothly and reliably. Proper clutch adjustment is more than just fixing a problem; it’s about preserving the integrity of your transmission, preventing premature wear of critical components, and maintaining the legendary performance of your MF 135. Regular checks and timely adjustments will keep your tractor ready for any task, ensuring it remains a dependable partner on your farm for years to come. Remember, a well-maintained clutch translates directly into a more productive and enjoyable tractor operation.
Image by: Elena Mozhvilo