On residential and commercial lawn mowers, you can sometimes start to hear a "growling" sound coming from the PTO clutch brake. These components are used to engage and disengage the cutting blades beneath the mower deck. These clutch brakes are also used on other outdoor equipment including aerators, top dressers, pavement cutters, stump grinders, portable sawmills, and more.

The clutch brakes are normally mounted on the engine shaft, with the pulley facing away from the engine. On the top side of the clutch, the coil body is supported by a ball bearing. The pulley side is also supported by a ball bearing. If you haven't guessed it yet, the growling sound comes from the start of a bearing failure. The idea is to be able to identify the issue and change out the clutch before there is a total failure resulting in unplanned downtime.

Both bearings are affected by the machine's vibration profile, particularly if a diesel engine is the power source. This can be rough on the bearings, although Ogura clutches are constructed to tightly control bearing internal clearance and minimize vibration issues. On the top side, the clutch is particularly affected by the engine heat, and the bearings are fitted with a high temperature grease for that reason. The harsh conditions, combined with abrasive materials, can sometimes help contaminants get past the bearing seals. This contamination will reduce the viscosity of the lube and help lead to premature bearing failure.

If you want to troubleshoot to determine which bearing might be failing, there is a simple test. If the growling goes away when the clutch is engaged, the problem points to the upper bearing – on the coil side. This is known because when the clutch engages, there is little relative motion between the inner and outer bearing race on the pulley side, pointing the finger at the other bearing making the noise.

Ogura GT series PTO clutch-brakes are made in a variety of configurations and typically mount on gas and diesel engines rated up to 40 HP. Bore sizes match the typical engine shaft sizes. Pulley sizes can vary based on machine requirements. Some have hub outputs to mount your own pulley, sprocket or coupling half. Clutch torque is rated up to 400 lb-ft on the larger units. These clutches typically operate on 12 or 24VDC.

Benefits of using an Ogura PTO clutch brake:

• Long life
• Safety
• Built for outdoor operation
• Many years of proven success
• For use with operator presence controls
• Available with a soft start controller
• Custom designs available based on minimum order quantities

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