New to the forum and with my hay bale loader (large bales)

[huskerredx]

How did you find PF?: Found on google, was the top rated physics forum on there. I need help!

I posted 2 pictures above. I’m a rancher/farmer. I grow my own feed for our cattle (outside of natural pasture, as pasture goes dormant in the winter). I built this bale mover to be able to haul bales to cows in the winter. The issue is, our bales are 5’6” long and weigh 1,300 lbs. I put a 2,000 lb winch on the bale mover I made, but it won’t lift them. Can someone help me as to how many pulleys to add, where to put them, and how much weight I will actually be lifting?

 

[jim mcnamara]

Moving the thread to Engineering - will get better answers there. Plus folks are going to need to some more details, so be ready.

 

[jim mcnamara]

Plus, I do not see a counterbalancing weight - I assume the trailer it attaches to the hookup on the back of the tractor - and the weight of the hay will not pull it loose from that connector.

 

[hutchphd]

It is not at all clear to me how this thing is rigged.
Also do you have reason to believe that the winch actually supplies 2000lbf of tension to the cable?

 

[russ_watters]

It looks to me like the bale gets stabbed with the forks and then the winch pulls on the frame to tilt the forks up and lift the bale off the ground. Is that what's happening? We need the height of the cable connection above the hinge, the horizontal and vertical distance from the hinge to the winch and the diameter of the bales (or are you stabbing them from the end?). It looks to me like based on the angle of the cable, the current mechanical advantage is less than 1. Just a pulley or two will do it, but you may as well hit this with a sledgehammer and make it several.

Big caveat/potential problem: are you trying to lift the bottom bale with the one piled on top leaning against it?

 

[Baluncore]

The 5' 6” ( 1676 mm) bale width suggests they start out as standard 5' wide by 6' diameter bales.

The bale is best spiked by the tines from the flat face, when the centre of mass will be about 2' 9” = 840 mm from the tine bar. Note that with the geometrical arrangement shown, it will only lift the tines to an angle of about 45° before the angles increase the winch requirement.

Judging by the picture, the length of the vertical mast is about right for a 1300 lb bale with a 2000 lb winch. What is the distance from the hinge axis to the attachment point on the mast?

Looking closely, I see a cable that I assume is used to power a 12 volt electric winch. I would question the thickness of the cables being used to connect the winch to the 12 battery. Do the cables get hot when the winch is stalled, which is when the current draw will be at a maximum? Most of the battery voltage may be dropped in the resistance of light weight cables. You could do a test with a pair of heavy jumper leads from the battery to the winch, or borrow some 100 amp electric welder cables.

There are several improvements possible.
1. Use really heavy cables for the 12 V connection, similar in capacity to the battery to starter cables in the vehicle.
2. Lengthen the vertical mast by a factor of about 1.5
3. Move the winch closer to the vehicle attachment point.
4. Use one pulley on the mast with the cable end attached to the trailer near the winch.

 

[Averagesupernova]

My guess is that the winch is not getting full voltage. Looks like a lot of wire in the pic that I assume eventually connects to the tractor battery. Too much loss.

 

[jrmichler]

Everything that @Baluncore said, while expanding on his comments about wire size.

Check the voltage at the winch when it's stalled out. Then check the voltage at the battery. If the winch voltage is more than about 0.5 to 1.0 volt less than the battery voltage, you need larger wires. If the battery voltage is less than about 11.0 to 12.0 volts, you need more battery power.

You could add two or three batteries to the bale loader, with wires to the tractor alternator. The tractor would charge up the bale loader batteries, which would power the winch through short, large cables.

 

[Twigg]

I'll second everything above, but I wanted to add that you might want to make sure the cable under tension (mechanical, not electrical) is in good shape and can handle the force (taking whatever combination of pulleys you end up using into account). After all, if that cable snaps, it will recoil towards the driver's seat. I know you probably don't have a lot of time for maintenance. Maybe just throw a sheet of 1/2" plywood behind the seat as a shield? Or whatever you have lying around. Just looking out for you, cause that cable sure looks thin

 

[Twigg]

Another thought occurred to me. If the OP is still reading this, try some WD-40 on the hinges (as a de-rusting agent, not a lubricant! don't wreck me in the replies! ). I noticed all the rust there and I'm wondering if the hinges are just seized and that's adding juuust enough resistance to stall the winch.

Also, if you have any leftover square tube from building the frame, just raising the winch higher might give you the same mechanical advantage as a pulley with no required additional parts. The more horizontal the steel cable is, the better.

Nice build by the way! I'd love to know how you aligned the parts of both hinges concentrically while welding if you have the time