Ask the Mechanic

Loose Drive Train

(Steve Thompson)

READER: I have a New Holland 488 Haybine. I like to use it on sudan hay because it does a good job of crimping/conditioning the hay, and the reel allows it to never clog up.

The problem with it is that it keeps throwing off the reel drivechain. It started after I had the top roll bearing replaced. The chain is a little loose, but I think the problem is caused by the chain sprockets not being aligned. I don't know how to adjust the chain tightness, because there is no idler on the chain. I can't get an end view to see if the sprockets are aligned. Can you help? I'm getting tired of getting off and on the tractor.

STEVE: I can help you with this problem, and it's an easy fix. The chain adjustment is located on the back side of the big driven sprocket. After you crawl under the back of the machine, you will see a lever with a cap screw in it. Remove the cap screw and rotate the assembly until the chain is snug but not too tight. Other holes for the cap screw are provided to secure the lever where the chain is tight.

As far as the sprocket alignment, you can easily check and adjust the alignment as needed by placing a straight object (like a piece of a yard stick) from one sprocket to the other (see the photo accompanying this article). When they both are aligned with the straight object, you will be good to go. You may have to remove the gib key in order to adjust the small sprocket on the top roll to align the sprockets. We will talk about gib key removal in next month's column.


-- Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email, and be sure to include your phone number.


Past Issues