Hydraulic Cylinder as track tensioner

[Kernopelli]

I definitely think a small cylinder would be fine as well as far as load is concerned. My thought is that you would want something with constant tension that allows for both belt stretch and shock. I think the hydraulics are going to provide a static tension which will work but I have a feeling that the belts will respond better to something with some give to them.....could be wrong, I usually am.:thumbsup: I think without some give, you are running the risk of accelerating the stretching of the belt. That's where I thought pneumatics would have the upper hand over hydraulics if using the belts, its ability to compress and rebound. The belts may be a whole lot tougher than I'm giving them credit for though, I'm not familiar with them.

I am a off road motorcycle guy though and I know how much a chain can stretch in a short time and it's hard to believe that some of the same principle wouldn't transfer over to the belts. After a while, it's not just an issue of constant retensioning, it's an issue of your sprockets and chain no longer being the same pitch. That's a big issue here.

 

[brain55]

Just as a side note. You probably won't want to use a hardware store grease fitting, they really aren't intended to hold any pressure. Go to an equipment dealer that uses grease cylinders for their tracks, they are typically rated for 10,000 PSI.

Brian

 

[David Devuono]

You just unscrew the grease fitting, or in my case I will tap a screw on plug, so just unscrew the plug. Its possible that they have built some special valving but I doubt it because you do not want grease to move past the piston or you would be greasing the tensioner all the time. The attached pictures are the size I found them.

 

[PILOON]

You just unscrew the grease fitting, or in my case I will tap a screw on plug, so just unscrew the plug. Its possible that they have built some special valving but I doubt it because you do not want grease to move past the piston or you would be greasing the tensioner all the time. The attached pictures are the size I found them.

Most aircraft landing gear legs or 'struts' are oleos.
OLEO stands for air over oil.
Basically a hydraulic cylinder with some oil in it and the air pressure controls the length.
When the aircraft hits the runway the air compresses therby absorbing the shock and the arrangement produces no bounce, just shock absorption.

For purpose of track tension, a closed cylinder with some oil and a suitable air valve (to increase pressure (for more tension) would do the trick without needing springs.

I would think that any heavy shafted hydraulic cylinder (single action OK) with one plugged pipe thread and the other with an air valve would do the job and eliminate the need for a pressure spring.

Someone mentioned snow plow cylinders which are generally single action.
Great, that'll work, just add air valve instead of hydraulic source.
The plow cyls are big shafted, single action, rugged and cheap!
Generally 2 lengths are available: (think, 12" and 16")

When I plowed with a truck I always knew if there was air in the cylinder as it gave just the kind of effects that you want for a track tensioning device.

The air valve you'd want is made by Schrader for aircraft and comes in pipe thread or O-ring style.

Good luck, have fun!

 

[Johndeere3720]

another idea may be a regular tractor top link. Yes, angle and position may be key since it could be possible to bend one but you have that constant tension that the link provides and adjustability so you can tighten or loosen the tracks if needed. Probably a category 1-3, your machine is fairly small so you could probably get away with a category 1 or 2.

 

[porky69]

If you do use a grease zerk (Or screw in plug) and "just unscrew it" to relieve the pressure be careful as this could be dangerous, or should I say WILL be dangerous. If you have more than a couple of psi pressure in there it will shoot the zerk with a lot of force (ever use an air cannon to shoot potatoes).

You would be better off to have an on/off valve that could block the pressure and then make sure it points away from you when releasing pressure.

 

[David Devuono]

I like the top link idea. Given the rubber track and air filled tires, there will be room for debris to go. And $35 a piece is better then $100 a piece for a cylinder. I can always use extra top links if they don't work. I broke the threaded bolt on one of my top links when a homemade plow binded up. The 2700lb lift force on the 3PTH twisted the thread like it was rubber.

 

[Johndeere3720]

I like the top link idea. Given the rubber track and air filled tires, there will be room for debris to go. And $35 a piece is better then $100 a piece for a cylinder. I can always use extra top links if they don't work. I broke the threaded bolt on one of my top links when a homemade plow binded up. The 2700lb lift force on the 3PTH twisted the thread like it was rubber.

Glad i could help. wow, $35 a piece. Thats kinda spendy. They sell for around $20 around here. What category will you opt for? 1 or 2?

 

[David Devuono]

Cat 1 are about 20 " pin hole to pin hole which might be two long, I am leaning towards a 4 or 6" stroke cylinder. (12-14 inch long).

 

[David Devuono]

I picked up two new 6' stroke plow cylinders. They are 1 1/2 in bore with 1 1/2 inch shafts. Unlike a dozer, my unit has both suspension and air filled tires (for now) so there will be give in the system. The cylinders were only $31 a piece. I have done nothing in the past two weeks.