Dutch Posted October 27, 2003 Posted October 27, 2003 For all those who ask about the “correct” pulley diameter and the “correct” belt length for snowthrowers, mower decks, and other attachments, here are a few things to remember. Let’s say the OEM PTO pulley for a particular tractor is 4”, and the OEM pulley for the proper attachment is 4”. That gives a pulley ratio of 1:1. Now, let’s say you install an attachment from another model tractor, and the pulley is 5”. The OEM belt will be too short, and the pulley ratio will be different. To maintain the 1:1 ratio, you need to either replace the PTO pulley with a 5”, or replace the attachment pulley with a 4”. If you replace the PTO pulley with a 5”, the OEM belt will be too short, and you must use a longer belt. An attachment from one tractor may bolt up to another tractor, but the pulley may be either smaller or larger. Neither OEM belt from either tractor will work properly because the pulleys are mismatched. Determining what the OEM pulley sizes are supposed to be requires research in parts manuals. There are no easy answers.
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