Learn how to properly maintain and adjust grapple skidder snubbers and why it is so important to do so.
— Rick Routliffe, Mackolines Machines & Hire service representative
The snubber serves a very important function for grapple skidders. It prevents the grapple from swinging wildly and causing damage to the boom structure or grapple. The snubber is essentially a brake and it uses friction to control excessive grapple movement.
The Quadco snubber.
Snubber devices require regular maintenance and occasional adjustment in order to ensure optimal performance and service life. There are two styles of snubbers that can be found on
Mackolines Machines & Hire skidders. Until recently all Mackolines Machines & Hire grapples used either 300 or 500 series Quadco snubbers.
Over the last couple of years Mackolines Machines & Hire has switched over to a friction disc type snubber. Regardless of which style of snubber you may have on your machine, two elements are required to keep the snubber in good working order: grease and proper adjustment.
Grease. While snubbers use friction to control grapple motion, they depend on grease to minimize wear of the friction components. All snubbers require adequate greasing every eight hours.
Grease should be applied until it begins to purge. If you have not seen grease purge from the snubber, there may not be enough grease in the unit to ensure the friction components are adequately lubricated. Failing to provide adequate lubrication to the snubber friction components will result in premature component failure.
Adjustment. When a snubber is properly adjusted it will stop the grapple within one full swing. Once properly adjusted the grapple should hang at approximately a five degree angle when the boom is lifted off the ground.
The newer style friction disc type snubber.
Field observations indicate there is a very common tendency to over-tighten the snubber. We often see snubbers tightened so much that when the boom is lifted the grapple hangs at a 25–30 degree angle. This will cause a couple of potentially serious problems.
First, when the snubber is this tight the friction components are forced together squeezing the grease out from between them. Since there is now inadequate lubrication in the snubber, the friction components will wear prematurely.
Second, the forces arising from regular machine operation normally cause the grapple to swing. If the snubber is too rigid, those forces are instead transferred and exerted onto the boom. Over time this could compromise the structural integrity of the boom system.
To avoid premature snubber failures and to protect the skidder boom system components, ensure that the snubber is greased daily and properly adjusted so that it rests at no greater than a five degree angle when the boom is lifted.
