CARDAN SHAFTS

A Cardan shaft is a flexible mechanical coupling used to transmit torque between two shafts that are not perfectly aligned. In hydraulic systems, it acts as the critical link connecting the PTO (Power Take-Off) unit on the truck's transmission to the hydraulic pump or compressor.

This connection is vital when the pump cannot be direct-mounted due to space restrictions on the truck chassis.

Choosing the right shaft is critical for safety and performance. You must define:

• Torque Rating: The shaft must handle the max Nm output of the PTO (Power Take-Off).
• Flange Standard: Check if your PTO and Pump have ISO (4-bolt), SAE, or UNI flanges.
• Length: Measure the distance between the PTO face and the pump face (Compressed vs. Extended).

A telescopic cardan shaft contains a sliding spline mechanism that allows it to extend and compress (change length) while rotating.

This is essential in mobile applications (like tippers or garbage trucks) because the distance between the PTO (Power Take-Off) and the driven equipment changes constantly due to chassis flexing and suspension movement.

Vibration is the enemy of hydraulic systems. Common causes include:

• Excessive Angle: The angle between the PTO (Power Take-Off) and the shaft should generally not exceed 15-20 degrees.
• Phasing Error: The yokes on both ends of the shaft must be aligned (in phase).
• Worn Components: Damaged cross bearings or splines.

The difference lies in the number of joints:

• Single Cardan: Has one U-joint. Good for very short, direct connections with minimal misalignment.
• Double Cardan: Has two U-joints connected by a tube. This is the industry standard for connecting a PTO (Power Take-Off) to a remote pump, as it can handle parallel offset and greater angles.

To prevent failure of the PTO (Power Take-Off) drive line:

• Greasing: Lubricate the cross bearings (trunnions) and the sliding spline every 250 hours or monthly.
• Inspection: Check for "play" (looseness) in the U-joints. Any play means the bearing is worn and needs replacement immediately to avoid damaging the PTO housing.

Yes. Often, a PTO (Power Take-Off) may have a 3-bolt UNI output, while the cardan shaft has a 4-bolt ISO flange.

Hayneks offers high-strength Adapter Flanges and couplings to seamlessly connect different standards, ensuring you can use the right shaft for your hydraulic application.