HST pedal not returning to neutral

[deepsnow]

Thought I had a sticking pedal. Loose lock nut on the bottom side of the piston spring housing located below the ignition switch (NH TC25D). The dealers service techs told me to check out three Boomer problems: 1.Stretching/expanding plastic fuel tank causing the plate to which the cruise mag locks onto to get hung up on. Simple fix is to cut down the plate. Grinding a slow option. Bad news would be a damaged fuel tank; 2. Damaged linkage; 3. loose lock nut. No problem with #1 or #2. The lock nut under the upper rubber dust cap was on tight. Pedal moves freely but I still have rearward creeping. After scratching my head for couple days I took a closer 2nd look. Another lock nut on the bottom side of this dampening/positioning shock. A little trial and error to determine the correct length of the shock rod. No more crreep. Now I'm getting paranoid. How many other unexposed nuts are loose. Or maybe I'm the only loose NUT.

 

[jinman]

It sounds to me like you did some thorough troubleshooting. Good job! Thanks for the info. I force myself to look for loose hardware at least once per month. I don't like doing it, but so far, I've found several loose or undertightened fasteners. It just goes along with tractor ownership. /w3tcompact/icons/smile.gif

 

[Mosey]

I'm confused about what your problem was. When you said "HST pedal not returning to neutral", does that mean you let up on the pedal and the tractor kept going because the pedal did not return to neutral? What exactly do you mean by the "rearward creeping"? Thanks.

 

[Steelfan]

Mosey,

I think what Deepsnow is referring to, is when you let up on the HST Pedal, the tractor continues to creep. I have the same problem, but mine is a "forward creep". I was waiting for someone to post something on this problem. Its a bit annoying, and can be dangerous if you forget to set the brake.

Deepsnow,

I've got a TC21D, I'm having a bit of a problem with the location of the second nut that you mentioned. Are you saying that its on the bottom of the rod that runs into the pedal itself? I'd be grateful if you could let me know. Thanks for the post on something, that I'm sure happens quite often. Also I've found quite a few loose nuts, and such on my TC. I check them quite often since the beginning of summer, when my PTO box on top of my MMM left loose. I was very, very lucky, that no damage was done. I shut the MMM down right away. Also I found out that the first owner of this tractor had the same problem. He put locktight on the bolts, which was not a good thing to do. The bolt sheared off, and the others loosen, causing me a real problem. Locktight is not the answer, preventive maintenance is. Thanks again

Kent

 

[deepsnow]

Kent,
The lock nut and rod are part of the dampening shock (I don't know what the correct name for this part is) that is located under dash behind the right side panel (TC25D). Only the panel needs to be removed to expose the "shock". The "shock" is ~6inches in length & 2inches in diameter with a rubber boot cap top & bottom. If you look on the underside you will find the lock nut & a short length of the rod. Slide the lower boot up and depress the HST pedal foward to expose a flatten part of the rod. Adjust length by loosening lock nut & turning rod while holding the pivot linkage connector (it has a flat surface for ?12mm wrench) Counter clockwise viewed from top gives the HST pedal a bias toward foward. Before you do anything make sure the nut under the top boot is tight & look at or measure the position of your HST pedal relative to the floorboard stop bolts for a reference point .

 

[RocketJSquirrel]

I have noticed that some folks have mentioned they especially have the problem with the HST not returning to neutral when the tractor is under load. I normally do not use our 1320 at work, but today I used it a lot, and that's exactly what it does. For example, I was pulling heavily into a full bite, teeth down, with the box scraper. I let up and the tractor keeps pulling. I don't mean creeping, I mean pulling. After a moment it lets up. It did it several times.

I don't imagine a shock adjustment curing that, but I'll check. I am thinking NH has a long-standing design flaw here.

OTOH this tractor has a clutch. Maybe I am supposed to push in the clutch all the time? That seems contrary to the spirit of HST.

 

[Mosey]

What is the purpose of the "shock"? The problem I have is the one that RocketJSquirrel talked about - "HST not returning to neutral when the tractor is under load".

 

[MikePA]

<font color=blue>What is the purpose of the "shock"? </font color=blue>
My guess is that the shock serves 2 purposes. (1) Provides the 'feel' to the HST pedal by offering resistance when you push on the pedal. This resistance would also prevent abrupt swings in the speed of the tractor that a direct connection from the pedal to the transmission would cause. (2) Returns the pedal to neutral when you let off.

 

[Mosey]

Mike, if your guess is right, and it does make sense, then if the shock were stronger it might eliminate my problem. But, if it were too strong it might make it too hard to push on the pedal comfortably. I still don't understand what the lock nut adjustment is affecting. I guess I need to pull that panel off and take a close look at the shock.

 

[MikePA]

<font color=blue>I still don't understand what the lock nut adjustment is affecting. </font color=blue>
Guessing again...When you press on the pedal, it extends the shock piston. when you let off the pedal, normal shock action pulls the piston, and therefore the pedal, back to neutral. How far the piston retracts into the shock is controlled by the lock nut. If the lock nut isn't at the right position it might stop retracting the piston before the pedal returns to neutral.