Apr 302017
 

I discovered an issue with the alignment between the backhoe and its subframe on my tractor, which is getting it a free vacation at the dealer’s shop so they can take a look at it. I’ve also made a simple little upgrade to the implement height adjust lever stop.

The BH77 backhoe mounts onto a subframe which is bolted to the tractor’s frame. This subframe has two hooks at the bottom for the backhoe to drop into, and two pin holes at the top to pin the backhoe into place. When installing or removing the backhoe, you force the backhoe bucket against the ground to push the backhoe firmly against the subframe. Bosses around the pin holes on the subframe rest against pads on the backhoe, and this lines up the pin holes perfectly so that the pins can be easily inserted or removed.

BH77 Subframe Alignment

BH77 Subframe Alignment

On my tractor, only one of the bosses contacts its corresponding pad, and just barely at that. This makes one of the pins hard to install and removed. My tractor is going back to the dealer in a couple of days so that they can take a look at it. I have a feeling that this will probably just require a simple adjustment.

I’ve also made a very simple upgrade to my tractor. There is a sliding stop which you can use to limit the travel of the lever which controls the height of the rear 3-point hitch implement. When you are setting up an implement such as a brush cutter, you can adjust the stop to make it easy to repeatably lower the implement to the same operating height after lifting it up.

Implement Height Lever Stop Thumbscrew

Implement Height Lever Stop Thumbscrew

It is necessary to screw down the thumbscrew pretty tightly to keep the stop from sliding when you bump the lever against the sliding stop. The thumbscrew isn’t easy to grip tightly enough because of its shape, size and location. I found a very simple way to make the sliding stop easier to use. The thumbscrew is a pretty ordinary M6 screw, with 1mm pitch and 20mm length. I simply replaced it with a cam-locking screw with the same kind of threads.

Thumbscrew Replaced with Cam Screw

Thumbscrew Replaced with Cam Screw

This cam locking screw is part number 5720K31 from McMaster-Carr. It’s a bit finicky to get it adjusted just right the first time, but after doing so it is now much easier to adjust the implement height lever stop.

Update 2017-06-14:

The dealer fixed the backhoe subframe alignment by shimming the upper mounts with washers. Everything seems to fit just fine now.

Subframe Alignment Fixed (Left Side)

Subframe Alignment Fixed (Left Side)

Subframe Alignment Fixed (Right Side)

Subframe Alignment Fixed (Right Side)

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