Floppy Belt Pulley Brake

and/or Fork Shaft (JD-A)

(6-14-2009)

 

If I am reading this correctly, there is a bit of work to do to make that one like new again, but it can be done -- 'been there & done that! Before we get started here, however, I must say that if you do not have the proper manuals for your tractor, you are driving blind. See the 4-page listing of Deere publications posted on the JD-H website which is, BTW, http://www.jdhpubs.com/ There is a wealth of free tractor information for you there. You really need to print the 4-page pubs list document -- it is probably the only written reference or catalog to Deere Publications for tractors in the "lettered series" era you will find anywhere. Find your model designator & serial number in the chart, and then (if you need the books) call (800) 522-7448 with your tractor's model designator & serial number at the ready for Deere Pubs. At minimum you need to buy the Deere Pubs -- Operator's Manual and Parts Catalog from Deere, or from somebody -- just don't buy SM2000 as a "service manual". See the JD-H Restoration website (above) article called “SM2000-Beware!” that tells you about that one.

 

As I discuss your issues, I will be referring to PC 675 (JD-A Parts Catalog, page 21), "First Reduction Gear and Clutch Operating Parts". I also will be specific with part numbers. Always try to be part number specific when you go to buy or talk parts. And if you are new to John Deere, all parts are to be procured by model number and serial number -- forget year! There are many out there who don't even agree on the years for a given serial number because there are two lists out there: (1) Calendar year and (2) Model year. Example: Deere began producing 1940 JD-A tractors in July of 1939 -- a widespread practice in industry even today as in automobile manufacture. So don't worry about year. Model & serial number are key items of information.

 

 

First Reduction Gear Cover & Clutch Operating Parts

Now -- As I understand, your belt pulley brake arm is kind of flopping around; quite loose to be frank. You wondered if this would be a problem if you continued to operate with it as it is? Yes, and no is the answer. If you drive the tractor very little and do not use the pulley brake to stop the tractor, it will perk along for a long time yet. The downside is that by being out of kilter, you have uneven wear of the belt pulley brake lining (if any remains), and also you probably have metal-to-metal contact between the pulley brake arm and the belt pulley -- not good! This situation can be fixed. Reference drawing above: What is causing the looseness is "over-the-years" wear of the interface between the AA235R belt pulley brake arm (49) and the A603R clutch operating fork shaft (35). NOTE: An operator should NEVER use the belt pulley brake to stop the tractor!

 

I resolved this problem on my 1941 JD-A by disassembly, then and having the fork shaft (35) built back to its design diameter plus installation of a corresponding bushing into the top of the belt pulley brake arm (49). I am recalling shaft diameter to be 7/8" and a quick check of an unworn parts of the fork shaft (35) will reveal true shaft diameter in a heartbeat. I hired a machinist to build the fork shaft up and the mill back to diameter. NOTE -- If the fork shaft is loose in its A21R fork bearing (44), the A21R bearing casting also could be over-bored and suited with a bushing with fork shaft ID. The key will be alignment of the over-bore with the axis of the fork shaft.

 

I did have a problem with the belt pulley arm (49) after boring it out to install a bushing, this because boring weakened the top part of the belt pulley arm (49) such that after a few months of use, the remainder of the bearing section broke -- it was cut too thin. The solution here was to weld a small U-shaped piece of strap steel (used 3/4" wide 1/8" thick stock) around the back side of the bearing section of the belt pulley arm (49), this to ensure a secure "home" for the new bushing and all was well thereafter. I do wish I had taken some pictures of that repair -- it is a classic.

 

Disassembly is not too challenging here, but significant in how you do it. The first reduction gear cover does not have to be removed. See the drawing again. Disconnect the linkage to the clutch operating lever (27) by pulling the forward pivot pin (30) from the yoke (34) or clevis-like part. You then would remove the four small cap screws holding the A21R fork shaft bearing (44) to the first reduction gear cover (19). This entire assembly should now pull out of the tractor. Here you have to become extremely attentive to detail. Take notes, take pictures, be observant! The objective is to extract the A603R fork shaft (35) from this assembly -- doing it and recording the event so as to make putting it back together both easy and a certainty that you have the “recipe right”.

 

There is a spring (42), a snap ring (36), 16-gage safety wire (37), and a positional relationship between the A78R fork (41) and the A603R fork shaft (35) which MUST end up being the same as it was found before disassembly. STEP: Using a center punch, make two corresponding index marks -- on the fork (41) and on the fork shaft (35) BEFORE disassembly. The use these two marks to guide you during reassembly. [NOTE: You may already find two such markings -- and if so, make a journal note of them and use them during reassembly.]

 

Working Tractor?  Only need a new grip for braking?   Rather than peeling off the old worn-out lining, the practice has long been to install a "clip-on" one. This is JD part number AB4748R (Now RE29790) and is widely available from after-marketers and John Deere too. The price -- well, it varies from under $9.00 from Steiner Tractor Parts (800) 234-3280 to around $24 at your local JD Ag Dealer. ++++