using hydraulic motor as a brake drag

[rockinmywaypa]

The title is the best description that I can come up with. This is what I want to accomplish ..... I want to be able to control a cable so that it only feeds out from a drum at a certain predetermined linear force or drag or pull however you want to describe it. This is part of a machine I'm going to put together to pack silage into a bag, I want to hold the machine to the bag so that the cable attached to a gate at the end of the bag feeds out as the bag is being stuffed full but at a predetermined force on the plastic so that I know it is being packed full. I have tried a hydraulic orbital motor but the oil can flow through it even without much rotary force applied to it. would a gear pump/motor be positive enough so that it would hold against the turning force of the drum shaft until a bit of oil is released through a pressure relief valve but not until. The reason this appeals to me is because I could have an either/or valve and switch over to a regular valve to speed the cable in when the bag is full or between setups and then switch back when filling so that the filling force pushes against a pressure relief valve and it is self controlling. Sorry about needing to use a thousand words to get to one picture.

 

[oldnslo]

Is this direct coupled to the drum or is there some form of gear reduction between the drum and the hydraulic motor?

All hydraulic motors leak. Gear motors depending on the pressure differential across them will typically be around 80 - 85% efficient. Some forms of orbital are about the some are the worse.

Dumb question but... what do the companies that build these machines use?

Roy

 

[rockinmywaypa]

I had two ideas in mind for drum shafts. one was to have roller chain from a solid shaft with a drum on each end connecting to the motor/pump. the other was to use a scrap rear end from a pick up in order to use the gear reduction and a differential to keep both sides evenly pulling. All I can do is look at pictures on the internet and ag bagger has some sort of motor connected to their drums. I know one person about 20 miles away that has one so I may have to go see his to find a solution. I hope to find something that has the ability to let out cable according to the amount of preset pull on the drums and also be able to wind it up quickly as soon as the bag is full.

 

[oldnslo]

I have seen these in use but never been close to one so here are a couple of thoughts or items to consider.

Is the hydraulic unit going to be a self contained unit or operate off of tractor hydraulics?

if tractor hydraulics will it always be run by the same tractor?

My experience, though a little dated, was that different models and brands of tractors operate at diffent pressures and flow rates. These could and probably will have some effect on how the machine operates unless you have pressure and or flow controls for some functions.

Also may have some open center and some closed center models.

Not sure how much tension/torque you will require for stuffing the bags but you may talking about a fairly large displacement motor. Eaton Char-Lynn and probably other companies have two-speed motors for winch use. Low Speed High Torque and then High Speed Low Torque. I also believe most heavy duty winches incorporate some form of brake.

May also need to consider some way to "take up the slack" if sitting idle for a period of time like a rain delay or over night. Depending on circuitry may even need this if crop is light and there is a lot of time between loads.

good luck

 

[Treemonkey1000]

Maybe I am not getting the whole picture of what you are doing. And that wouldn't be the first time for me. Can you put a electrical limit switch underneath the platform holding your bag of whatevers. Fill the bag until it flexes the platform enough that your limit switch activates a shut off valve on your chute?

 

[Snaker]

Fluid would be good for rate (speed) regulation but I don't know about cable tension. I'm thinking mechanical. How about a spring loaded idler pulley arm on the cable. When the cable tension is reduced, the idler arm would displace and through adjustable linkage, would engage a mechanical brake shoe.

 

[oldnslo]

I believe the OP is talking about filling silage tubes. These are the long white plastic tubes you see laying by feed lots etc. My uncle helped fill a couple of these a few years ago and I think he said it took 100 HP minimum to run one of these filler/packer units. I think the tractor and machine is pushed forward once the bag gets heavy enough. These hold several tons of feed and are compressed to some pretty heavy loads.

Roy

 

[rockinmywaypa]

you are exactly right oldnslo. Rather than rent and have to be in a hurry to get done in a day I think I would like to build on the idea and use a hydraulic cylinder to pack the material in instead of a rotor that takes gobs of horsepower. If I can get around this thing about releasing cable as the bag reaches it's optimum amount of capacity then I'll go ahead and start building for next year. A mechanic at work suggested that I go with electric brake motors and use an electrical switch to gauge how much is in the bag, I may have to explore that option. I really wanted to keep it simpler than that though.

 

[kubotakid USA]

Ive seen them built localy, and he uses a air brake trailer axle, and sets a desired amount of drag on the axle brakes by turning a little hand wheel, to adjust the brakes, about as simple as you can get, Eric

 

[oldnslo]

Ive seen them built localy, and he uses a air brake trailer axle, and sets a desired amount of drag on the axle brakes by turning a little hand wheel, to adjust the brakes, about as simple as you can get, Eric

Are they using the manual adjustment on the brakes or adjusting air pressure to the brakes? Either way sounds like a neat and simple idea.