Thursday, May 25, 2006


When last we left our hero, he had just received some help from the pros...

As part of the troubleshooting, it was going to become necessary to disengage all of the safety features of the tractor. That's what the little fittings were for. As the mechanic explained to me, "Everything in the transmission tells the tractor to go. Everything in the steering column tells it when not to go." The first step was to disengage the steering column valves from the transmission, thereby overriding the safeties. One thing to keep in mind when overriding the safeties is that you can now be killed by what you've just done, so it was time to jack up the back wheel. If the wheel is jacked up, that means that it will spin freely and the tractor won't go anywhere, like over the top of your head.

I think I've got to step back a bit and explain a few other things. I work with my dad, all day, every day. We don't do things the same way, and even though my way works, his is the "right" way to do things. The next thing is that I hate watching American Chopper with a passion. Most people LOVE that show and can't figure out how I can't like it. I don't like it because I LIVE it. My dad and I are just like Paul and Pauly, only the names and shapes have changed. I can't do anything right, and what I tell him he doesn't believe. For example... every time we have to measure the length of something, the conversation always goes like this:

Me: "Here take this tape and go over there so we can measure it."
Dad: "You take this end, I can't read the numbers."
Me: "No, you take the number end, you won't believe me if I tell you what it says, you never do."
Dad: "That's a bunch of crap. Just take the damn end and go. ... What's it say?"
Me: "73 and 7/8 inches."
Dad: "That can't be right, here let me look..."


Ok, now guess who wasn't jacking the wheel up correctly? You got it. Me. So after a short 5 minute yelling contest we finally got the wheel jacked up "correctly". Then we unhooked the little hydraulic lines leading to the steering column and put the little caps on them, fired the tractor up and voila! The problem was in the transmission. We'd dismantled the entire steering column the day before for nothing. I was so proud, but at least we knew the problem was in the transmission.

Of course taking apart the tranny involved draining out all the oil I'd just put in that past January, but what the hell. Might as well double up on everything while we're at it.

If you ever have to fix something like a car or tractor, go ahead and buy the service manual. They're kind of spendy, but when you've never done things before, it's worth every penny, and they have pictures!

As I've already explained, the innards of a hydrostatic tranny don't have gears, rather they have little piston like creatures called the motor servo and the pump servo. When the piston extends one way, the tractor is able to pump more hydraulic fluid and it goes forward. When the piston extends the other way, the tractor pumps more hydraulic fluid in the opposite direction and the tractor goes into reverse. My piston was stuck at the far end of reverse.

According to the mechanic, that meant that one of the little orifices in the servo was probably plugged and wasn't allowing it to reach equilibrium, or neutral. The only way to know was to take the servo off.

Once we got the servo off and taken apart, we could see that the inner part of the piston plunger was scarred slightly. The scarring wasn't very bad, but it was there none the less. The little orifices were completely free from debris, so we could only guess that the scarring was somehow keeping the piston from it's smooth operation. The strange part is that we couldn't see what had scarred the piston. This is always troubling, because the thing that leaves a mark on a solid piece of metal is usually damaged as well.

I drove down to the dealer and went through his part book to make sure that he ordered the correct part and seal kit to replace the marred piston, and they had it shipped out straight away.

A few days later, the parts came in and I drove back down to the dealership. The fellow that had helped me the first time was busy so another guy got the part for me and started a ticket. "Proud of that sucker, ain't they." he said. Now when a parts guy says something like that, you know it's gonna pinch a little. $600 for the piston and the seal kit was extra, but what are you going to do? I took the part and went home.

When I finally got around to putting it all together, things worked rather smoothly. The servo went together without a hitch, the servo went back in the tractor like it should, and every other part fit just like it was designed. I was starting to feel good about the situation. That was my next mistake.

As I began to put on the final inspection plate, I looked down in the remaining dregs of hydraulic oil that always clings to such parts and there it was... one third of a broken snap ring.


Blogger trinamick said...

"My piston was stuck at the far end of reverse."

That sounds like the beginning of a Viagra ad.

I can't work with my mother. My dad? No problem. My grandpa? Just fine. But her? No way. We are on different wavelengths, and she questions my methods constantly, even though she can't explain herself to save her life. It's like being pecked to death by a duck.

5/26/2006 2:37 PM  
Anonymous bc said...

Now you know what I go through with my father. He is just like that. But at least I finally convinced him to get a new vacumm cleaner.

5/26/2006 5:26 PM  

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