Ask the Mechanic

Steve Thompson, Contributing Columnist

READER: I have a question about how to hook up a drag mower I bought for my International 656. After I hook the hitch to the drawbar, the PTO shaft on the mower is too long to slip on the PTO shaft of my tractor. I believe the previous owner had an International tractor. I have never hooked anything to the swinging drawbar, and I am not sure if it is the correct length. What should be the length of the drawbar?

STEVE: Your question is an area that is of concern on many tractors. The drawbar's standard length is 14 inches from the end of the PTO shaft on a tractor to the center of the pinhole in the drawbar. This measurement is a standard measure for any implement turning at 540 rpm. If the implement is a 1,000-rpm shaft, the length should be 16 inches from the end of the PTO shaft to the hole in the drawbar. This measurement is critical because the PTO shaft must have room to telescope and recede as ground terrain changes when pulling a drag implement, and as the mower is raised and lowered on a 3-point implement. Many times, new tractors come from the factory with the drawbar placed as far under the tractor as possible for shipment. Without proper drawbar length adjustment, an implement hooked to the swinging drawbar can appear to be too long. Don't cut it off until you have adjusted the swinging drawbar to the standard setting for the speed of the PTO. If the driveline on a drag implement is a three-joint, with the proper length of the drawbar, the adjustable "tipping bearing" should run close to vertical with the tractor parked on level ground.

> Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email mechanic@progressivefarmer.com.

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