Suspension Systems for Mower Decks on Lawn and Garden Tractors

Richard L. Parish  |  12/1/2004 10:43:26 PM

Mid-mount rotary mower decks are common on lawn tractors, garden tractors, subcompact tractors and smaller compact utility tractors. There are two ways these decks can be mounted, and the mounting method affects adjustment and operation.

Suspended Decks
Smaller tractors generally use suspended decks. They are found on most lawn tractors, lawn and garden tractors, garden tractors and even some subcompact tractors. Suspended decks hang under the tractor on a parallelogram linkage. An adjustable stop link limits the rotation of the parallel linkage and determines the height of the deck. The adjustable stop may controlled by a knob or lever on the tractor. In operation, the deck is lowered until the linkage hits the stop and is suspended there.
 
With suspended linkages, the wheels and rollers on the tractor are not designed to contact the ground in normal operation. The wheels and rollers are designed only to prevent scalping when uneven ground is encountered. You must adjust the height of the wheels and rollers to correspond to the height setting chosen, so that the wheels or rollers are carried just above the level ground surface.
 
If your anti-scalp wheels or rollers touch the ground all the time, they are not properly adjusted and will experience excessive wear. They are not designed to be gage wheels. See your operator’s manual for instructions on proper adjustment.

Ground-carried Decks
The decks on most compact and some sub-compact tractors are ground carried or ground following. The linkages on these decks look very much like the suspended linkages used on smaller tractors but are not necessarily parallelogram linkages. On these tractors, the linkage lifts the mower deck for transport and pulls the deck along while mowing; it does not carry the weight of the mower when in use. With ground-carried decks, the deck rides on gage wheels when in use. The wheels are generally much larger than the anti-scalp wheels on suspended decks and usually have pneumatic tires, not just semi-pneumatic tires.
 
With ground-carried decks, you will either lift the deck all the way up into the transport position, or lower the linkage all the way; you do not want to carry the mower on the linkage in use. Either the front or rear linkage (or both) will pull the mower deck along while mowing, but the mower will follow the contours of the ground, independent of the tractor. Height adjustment is accomplished by moving the gage wheels and rollers up or down, typically using adjustable pins or collars. Once again, see your operator’s manual for instructions on how to set the wheels and rollers.

Suspended decks are used on smaller tractors and ground-carried decks on larger tractors. Both types of mower suspension work well. You do, however, need to recognize and properly respond to the significant differences in how they are adjusted and used.

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