Help with lever and fulcrum math

[ken erickson]

I am fabricating a lift mechanism for my L2501 and was hoping someone with better math and engineering skills than I could help out.

I am attaching a drawing that should explain what numbers I need. Or what would be the formula?

The 21 inch bar will be attached to a trolley at right angles to the center line of the trolly wheels , equal distance to each wheel.

Thanks in advance.

 

[BigG]

Are you using a winch to move the trolly up and down? If so where are you going to attach it to the trolly?

 

[ken erickson]

Are you using a winch to move the trolly up and down? If so where are you going to attach it to the trolly?

Yes, I will be using a winch. The cable attachment point will be 2 3/4 inch out and inline with the top trolley wheel. The winch cable will be a few degrees off of vertical away from the attachment point.

See new picture.

 

[dlsmith]

You need to find the ratio of the length of the two arms on the lever.

In this instance the ratio is 21" / 2.375" which equals 8.842.

So the force exerted on each of the rollers on the 2 3/8" arm is 160 lbs X 8.842 or 1414.7 lbs.

Hope this helps.

 

[ken erickson]

You need to find the ratio of the length of the two arms on the lever.

In this instance the ratio is 21" / 2.375" which equals 8.842.

So the force exerted on each of the rollers on the 2 3/8" arm is 160 lbs X 8.842 or 1414.7 lbs.

Hope this helps.

Being that the 21" arm meets in the center of 2 3/8 total wheel spacing with 1 3/16 from center to wheel on top, and 1 3/16" from center to wheel on bottoms, would the force on each wheel still be 1414.7 lbs or 707.3 on each for a total of 1414.7?

fyi, here is a picture of the "c" channel that the trolley rides in.

 

[BigG]

It has been a long time since physics class but I wanted to try.

21- 2.75 = 18.25 in.

18.25 x 160 = 2,920 in.lb

2,920 / 2.75 = 1062 lb

1062 / 2 = 531 lb on each end of the trolly

It is not 100% but it is close enough so you know how to build it.

 

[Ping]

Ken
Been several decades since college. Assuming this is static (dynamic force calculations make my head explode) and the winch cable is verticle ( makes math easier).
Looks like force on each trolley would be 1229.5#
Sum forces in Y = 0
winch - 160# load. Ie winch load will be 160#
Sum moments about top trolley axle = 0
2.75” x 160# - 160# x 21” + 2.375” x Trolley Bottom= 0
Tb= 1229.5#
Sum forces in X = 0
1229.5 - Trolley Top = 0
1229.5# = Tt
Hope this helps
Regards

 

[dlsmith]

Being that the 21" arm meets in the center of 2 3/8 total wheel spacing with 1 3/16 from center to wheel on top, and 1 3/16" from center to wheel on bottoms, would the force on each wheel still be 1414.7 lbs or 707.3 on each for a total of 1414.7?

fyi, here is a picture of the "c" channel that the trolley rides in.

Let's assume for a minute that the arm pivots at the end roller.

It's simple to calculate the force generated by the 160# at a 21" arm, it it 160" X 21" which is 3,360 in/lbs.

A simple proportion let's us calculate the force on the roller at 2.375" from the end.

Force1 X Arm1 = Force2 X Arm2

So the force on the roller 2.375" is 3,360 in/lbs divided by the 2.375" arm which again equals 1,414#.

If the force on that roller is 1,414#, the force on the other roller has to be the same, or 1414#.

If the forces were unequal, the bar would have to rotate to try yo balance the forces.

Got it?

 

[BigG]

I hope you will show us the finished project.

 

[ken erickson]

Thanks for everyones help! I have a pretty good idea of the math involved and the forces I will be generating.

I will post pictures of completed lift assuming I do not have to completely re-engineer!

 

[ken erickson]

These pictures will give a better idea of where I am headed with the seat lift.
The base of the c channel is bolted to the loader sub frame with 3/8 5 inch u-bolts, no welding on the tractor or loader. The lateral support for the c channel is picked up from the loader frame pin that goes thru the loader and loader sub frame. This will allow my seat lift to remain functional with or with the loader installed. There will be a 5/16 grade 8 bolt that runs thru the heavy wall square tubing and the loader pin.

The seat arm will pivot at the trolley, again at about 6 inches and the seat itself will pivot. The wood pieces are just a mock up.

The c channel tower sets the 3000 lbs winch a tad higher than the highest point on the steering wheel for reference. I may have to tweak the location of the winch so the cable does not rub along the open ended portion of the c channel.
I will fabricate a guard or metal box over the winch to protect it from tree limbs etc.

The seat arm will be quick detachable.

Any thoughts or suggestions more than welcome!

 

[BigG]

Just wondering if you should or could turn the winch 90 degrees. Since you are pulling the arm up with the cable at an angle will the cable want to bunch up at the right side of the spool over time? If you turn it 90 degrees the cable could work across the spool.

Are you using a sling to get up to the seat height and then transfer or are you removing the factory seat and pinning the lift seat in place to operate from? Or mounting a seat on the arm and then transferring to the factory seat?

I like where you are headed with this.

Thanks for the pictures!

After looking at the pictures again, how are you going to push in the clutch with out hindering the movement of your legs?

 

[ken erickson]

Just wondering if you should or could turn the winch 90 degrees. Since you are pulling the arm up with the cable at an angle will the cable want to bunch up at the right side of the spool over time? If you turn it 90 degrees the cable could work across the spool.

Are you using a sling to get up to the seat height and then transfer or are you removing the factory seat and pinning the lift seat in place to operate from? Or mounting a seat on the arm and then transferring to the factory seat?

I like where you are headed with this.

Thanks for the pictures!

After looking at the pictures again, how are you going to push in the clutch with out hindering the movement of your legs?

I had considered turning the winch 90 degrees but thought the way I have it mounted now will give me the least obstructed view. I had also considered mounting the winch down low and using a top pulley. Hopefully as the travel of the trolley only needs to be about 19 inches the cable does not play out more than the first wrap. This winch has a spring type steel plate to keep a tight wrap even with no load. The mounting plate on top does allow me to change up pretty easy after my testing.

I will be using a small padded seat plate , raise up to clear the radius of the fender, then "swing" in closer to the tractor seat by pulling with my arms. I will then transfer to the tractor seat as is. I have good mobility considering and good arm strength. I "hike" myself into my B7100 from my chair using a hand hold that is mounted on my canopy frame. This Tractor of course sits much higher and is further from the side of the tractor to the seat. I could climb aboard this tractor as is from my chair but for the long run etc a seat lift makes sense.

I will be installing a quick detachable clutch rod but wanted to wait until I have the seat lift built and tested. I was on the tractor and was able to bend over and actually use my hand to depress the clutch but that is not a long term solution.
I have a solid mounted clutch lever on my B7100 that works out well.

Added a picture of the hinged seat arm and a mock up of the seat pan.

 

[D2Cat]

Ken, does the seat pan need to be rectangular? It looks like if it was round it would clear the fender and dash with out a chance of hitting either one as the hinge swings towards the seat.

You're doing a nice job.

 

[ken erickson]

Ken, does the seat pan need to be rectangular? It looks like if it was round it would clear the fender and dash with out a chance of hitting either one as the hinge swings towards the seat.

You're doing a nice job.

Thank you!

Rectangular will probably work best. This mock up is larger than the final size and I know for sure I can add more radius to the corners for extra clearance.

My 200 lb son stopped over and I had him sit on the extended seat arm and all was good as far as strength. The pivots also seems to offer about the right amount of resistance.

 

[GreensvilleJay]

wow ! I commend you for your efforts to 'keep on tractoring' !!!

 

[D2Cat]

Ken, I have a friend who had a severe injury to his arm. The Dr's. said he'd never be able to use his hand for much and never be able to carry any weight.

He got in the habit of carrying a 5 gallon bucket, then he add some water, then more water. Soon you could only see the scares because he developed the use through determination and discipline.

I admire folks who have gone through what ever it was that caused you the grief, but keep on with life as it it's no bid deal. Be blessed, my pal!

 

[ken erickson]

wow ! I commend you for your efforts to 'keep on tractoring' !!!

Ken, I have a friend who had a severe injury to his arm. The Dr's. said he'd never be able to use his hand for much and never be able to carry any weight.

He got in the habit of carrying a 5 gallon bucket, then he add some water, then more water. Soon you could only see the scares because he developed the use through determination and discipline.

I admire folks who have gone through what ever it was that caused you the grief, but keep on with life as it it's no bid deal. Be blessed, my pal!

Thanks guys!
I was 22, 63 now, when I had what I thought was a devastating spinal cord injury. I was working under a vehicle unsupported without jack stands. I came to the conclusion very quickly that life still had a lot to offer. It has been quite a ride so far! .
I purchased 56 acres 2 and half years ago and in process of restoring/creating Oak savanna/prairie. This work has progressed to the point now where my little B7100 was just not enough tractor going forward.

 

[ken erickson]

Getting closer with my seat lift.
I did however hit a snag.
I had purchased a new winch from the local farm supply store and had not bench tested it. After wiring etc I plugged in the hand held control and nothing!.
Did not feel right about taking it back for a refund or exchange as I modified the mounting bracket. Talked with the Manufactour and they shipped out a new winch to me yesterday.

I mocked up the padded seat pan but after sitting on it in the lowered position I will need to fabricate a pin lock to keep it from swiveling until I need it to.

Thus far I am happy with the geometry of the hinged pieces.

 

[D2Cat]

what is the seat pad made from? Looks like one of those thick pads you see at the lawn and garden stores to save your knees!