What are the PTO shaft oscillation and vehicle body vibration symptoms and solutions?

When the PTO shaft deteriorates, its bending vibration intensifies, causing driveshaft oscillation and even vehicle body oscillation, accompanied by periodic noise. This phenomenon becomes more pronounced as vehicle speed increases. While the vehicle is moving, the intense periodic vibrations generated by the drivetrain are noticeable, with variations in performance during acceleration and coasting. However, when the vehicle is stopped and the engine is running at various speeds, this vibration disappears.

Causes of PTO Shaft Oscillation

The primary cause of PTO shaft oscillation or vehicle body oscillation is driveshaft tube bending, which increases the amplitude of the driveshaft's bending vibration, leading to increased centrifugal force and severe vibration and noise. Furthermore, the maximum speed of a driveshaft is typically designed to be 0.7 times its critical speed. However, factors such as imbalanced driveshafts, damage to universal joints, and loose intermediate support bearings can reduce the driveshaft's critical speed. Once the critical speed drops to a level comparable to the driveshaft's speed, the driveshaft is susceptible to resonance during operation. During resonance, the drive shaft's amplitude is maximum, resulting in extremely severe vibrations that may even cause the drive shaft to break.

Determining Vehicle Body Shake and Noise

If the vehicle shakes when starting, accompanied by unusual chassis noises that become more pronounced as vehicle speed changes, this is often due to a loose connection between the universal joint and the transmission or rear axle flange, or excessive clearance between the spline and spline hub. In this case, the driver is advised to stop the vehicle immediately and carefully inspect these two critical areas, and manually shake the PTO shaft to further confirm the problem.

If the problem is indeed caused by a loose connection between the transmission and rear axle flange and the drive shaft, the connecting screws should be replaced and tightened to the specified torque. If the problem stems from excessive clearance between the spline and spline hub, the drive shaft may need to be replaced.

Checking for PTO Shaft Bend and Imbalance

If you hear a periodic noise from the driven disc while driving that increases with speed and, in severe cases, is accompanied by vehicle vibration and a numb steering wheel, this is usually due to a bent, twisted, or unbalanced drive shaft. In this case, remove the PTO shaft, carefully inspect it for bending and twisting, and perform a dynamic balance test. Also, check that the drive shaft's intermediate support is securely fastened to the chassis crossmember, and whether it is improperly assembled or damaged. Tighten or replace it if necessary.

Raydafon offers a variety of PTO shafts. For example, if the PTO shaft on a tractor is shaking, the following table provides solutions: