The downside of a tilting seat

SpringHollow · Apr 16, 2014

The mercury switches are angled and are basically limit switches. When tilted, they make or break contact which then control the hydraulic solenoids which control the supply of hydraulic fluid to the tilt cylinder.

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I used to have problems with it suddenly tilting but it works pretty well now. I do not notice any jerking but then the whole tractor is also bouncing round. It is very nice to have on side slopes.

Ken

cqaigy2 · Apr 16, 2014

I remember wheat combines in the 70's had mercury switches in them, i don't know what they are using now though. I also remember what fun it was if you happened to be on a steep side hill when the leveling mechanism decided to crap out and dump over to the down hill side. Getting out was real easy, all you had to do was open the door and fall out.

woodlandfarms · Apr 17, 2014

For me my issue of being dumped is purely electrical.

My complaint about the merc switches is that it takes a long time to come to level. If I am mowing steep and flip a U I tend to be facing down hill for too long. I have always felt the merc switches are outdated forms of leveling.

ponytug · Apr 17, 2014

Well, yeah...Have a look at your iPhone. To do one yourself, you would need to get a IC board for accelerometer, (or go whole hog for a gyroscope), a mini CPU to analyze the output, a DC to DC converter to live off of the PT power supply, and a MOSFET controller, with surge protection from the solenoids. Not hard, but not easy to make it waterproof, oil proof, dust proof and resistant to static electricity, voltage surges, kickback, and RF... Beyond me. Of course, being more accurate doesn't necessarily make it any faster, if the hydraulic solenoids are the slow part of the system. Might be cheaper to get a cheap android phone and hack an app to toggle a pin to drive the rest of the circuit.

Ironically, it was air bags that made accelerometers cheap enough for phones, and now the challenge is in the rest of the circuit.

All the best,

Peter

woodlandfarms said:
For me my issue of being dumped is purely electrical.

My complaint about the merc switches is that it takes a long time to come to level. If I am mowing steep and flip a U I tend to be facing down hill for too long. I have always felt the merc switches are outdated forms of leveling.

MossRoad · Apr 18, 2014

OK. So the switches are normally open. If the tractor tilts too far to one side, the mercury completes the switch on that side, activating a hydraulic solenoid that pushes or pulls the seat ram in the proper direction. Correct?

Is there and on and off switch for that tilting seat circuit to disable it when you want to? Oops, I see it was mentioned that there is a shutoff switch that was bypassed by the previous owner.

I also see mention of someone rebuilding their steering cylinders and then the seat worked better?

Hmmm.... as my PT425 is plumbed, hydraulic pump pressure to steering valve, power beyond port of steering valve to FEL valve, then back to tank. Is the red units with tilt seat plumbed the same way to provide pressure to the seat hydraulics after the steering valve?

As for an alternate seat circuit.... K.I.S.S. (keep it simple, stupid) comes to mind, and that's what the mercury switch circuit seems to be... very simple. It could get overly complicated to design a new circuit. And expensive.

I'm surprised no one has any complaints about bounce in the tilting seat on uneven terrain. It would seem the mercury would slosh around more, and without a delay in the switches, they would activate in a choppy fashion on rough terrain.

SpringHollow · Apr 18, 2014

I am not sure if Carl was referring to the kill switch in the seat being bypassed or the Tilt On/Off switch on the dash. My guess is that they work when bouncing around because both switches would be getting jostled and you do not notice minor adjustments. The solenoids/hydraulics add their own time delay to things. From my experience, if anything it is slow to respond.

Ken

woodlandfarms · Apr 18, 2014

Peter, thank you for ruining my day. I had seen those accel and tilt in phones and figured it would be a $2 circuit.

Moss, not sure on your situation

Ken - Yeah, so the on off switch for the seat on the dash never worked. Digging into it I found it all bypassed, the seat hot whenever key is on. I have not minded this, but I do detest the slow and inacurate response of the circuit.

To all, it is a single cylinder with a dual acting hydraulic control valve. There appears some sort of adjustment nob at the top of the valve so as the manual is so thorough I am going to have to call Terry. There are two merc switches on the back of the seat in a control box. I have to take it apart but the issue is in the merc switch and the cable being pulled too tight when I turn and twist just the right way.

cqaigy2 · Apr 18, 2014

Come to think of it, i have a little rc helicopter that has full cyclic control and a six way electronic gyro. When you initialize it the board, that is the reference it uses to determine changes in "level". The copter has two servos that connect to the blades to change pitch on the individual blades. You might be able to use the outputs from the board to drive an scr or relay to control a solenoid, so on and so forth.

There is a programmable flight controller called a multiwii that might be just the ticket.

MossRoad · Apr 19, 2014

woodlandfarms said:
Moss, not sure on your situation.

Married. Two kids. Employed. Decent health. Can't complain!

ponytug · Apr 20, 2014

I love it! It sounds like a great starting point for a hack- Carl would just need some darlingtons or power MOSFETs to drive the solenoids, and he should be good to go.

All the best,

Peter

cqaigy2 said:
Come to think of it, i have a little rc helicopter that has full cyclic control and a six way electronic gyro. When you initialize it the board, that is the reference it uses to determine changes in "level". The copter has two servos that connect to the blades to change pitch on the individual blades. You might be able to use the outputs from the board to drive an scr or relay to control a solenoid, so on and so forth.

There is a programmable flight controller called a multiwii that might be just the ticket.