Custom Loader for 520-H

[mattd860 162]

My father just had his knee replaced so during his down time, we are designing a loader for my 520-H. Once he heals (in a couple months), we will be ready to start welding it together. In the mean time, we will be designing it on paper and I will be acquiring the metal needed. If we go through with this, we will be fabricating and welding the entire loader and subframe from scratch.

Anyways, I need help with the hydro pump and lift cylinders. I'm not sure what to buy or how to size them properly. I would like the loader to lift a minimum of 1000lbs (although I will probably never attempt to load it that heavy).

Can anybody offer any advice?

[CRE1992 135]

Well Matt, it all depends what you want. Do you want it to have hydraulic down pressure on the bucket and lift arms for back dragging and leveling? Also you might want to sign up over at MTF as there is a guy named CADPLANS who does this stuff.

Check out his website at http://www.cadplans.com/907.htm . It should be of some help you. Also most large tractors like the john deere 790 my family has is only rated to lift about 900 lbs in the bucket. Its a 27hp diesel 4wd compact. However a shim kit is available for this to increase the stock hydraulic pressure to allow it to lift more. But a 520H does not have power steering, so you would most likey have to get a pair of tri ribs to help you out. Even when the bucket on the 790 is filled to max capacity, doesn't mean that you should do it. Larger tractors which can lift a lot and have heavier and stronger front ends than a 520. This is where a compact comes in. You might want to look into a used compact tractor with a loader before you do this. Only reason I am saying this there are many limitations with a garden tractor as opposed to a compact.

[mattd860 162]

I really just want a front bucket to load stuff in, like firewood, and then be able to dump it out without manually unloading it. I would like down pressure but don't expect to dig anything up or do any other work like that. It's primary function will be replacing the dump cart.

With that said - I think we're veering off topic. The question isn't should I get a loader or not, it's how should I size a pump and lift cylinders :)

[SousaKerry 501]

1000lbs I agree is a bit much for these tractors you can pick it up but you would not be able to move it well, Back on the farm we use loaders to move the big round bales 6'x5' they weigh in at about 700lbs IIRC and the Ford 960 with freeman loader was about all it could safely handle, now a wet bale will pick up 200lbs of water and the tractor strains to pick it up, it flattens the front tires enough to make the power steering all but useless and if you are not counter weighted with a bale on the back forks the rear end will loose traction and become tippy.

As far as pumps go I would look for a small belt driven gear pump in about the 5gpm range keep the maximum pressure to less then 1000 PSI (800 should be fine) make sure you use schedule 80 pipe at least you will burst schedule 40

Lift capacity is a simple equation take the area of the cylinder piston and multiply by the pressure in PSI so in example if your piston has a 1" dia the area is pie x r squared so

the area is 2.465 sq. in. x 800 psi = 1971.92 lbs of lift per cylinder.

The smaller the pump the longer it will take to lift figure the volume of your cylinder convert to gallons and that will give you how long a given pump will take to fill it so assuming our 1 inch cylinder has 20 inches of stroke is 49.3 cu in

is .213 gallons so...

two cylinders is .416 gal a 5 gpm pump with no loss or restriction should fill this in about 6 seconds.

Now all this is theoretical and many factors take away from this such as valve orifices and length of pipe and dia. of said pipe temperature of fluid, viscosity, and on and on and on.

Check out northern equipment, and or surplus center

[mattd860 162]

..... good equations and advice

Awsome! Thank you sir!!

[KC9KAS 4,741]

Sousakerry2 I know Mr. Pascal and his law!

Pascal's Principle and Hydraulics

SUBJECT: Physics

TOPIC: Hydraulics

DESCRIPTION: A set of mathematics problems dealing with hydraulics.

CONTRIBUTED BY: Carol Hodanbosi

EDITED BY: Jonathan G. Fairman - August 1996

Hydraulic systems use a incompressible fluid, such as oil or water, to transmit forces from one location to another within the fluid. Most aircraft use hydraulics in the braking systems and landing gear. Pneumatic systems use compressible fluid, such as air, in their operation. Some aircraft utilize pneumatic systems for their brakes, landing gear and movement of flaps.

Pascal's law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container.

A container, as shown below, contains a fluid. There is an increase in pressure as the length of the column of liquid increases, due to the increased mass of the fluid above.

For example, in the figure below, P3 would be the highest value of the three pressure readings, because it has the highest level of fluid above it.

If the above container had an increase in overall pressure, that same added pressure would affect each of the gauges (and the liquid throughout) the same. For example P1, P2, P3 were originally 1, 3, 5 units of pressure, and 5 units of pressure were added to the system, the new readings would be 6, 8, and 10.

Applied to a more complex system below, such as a hydraulic car lift, Pascal's law allows forces to be multiplied. The cylinder on the left shows a cross-section area of 1 square inch, while the cylinder on the right shows a cross-section area of 10 square inches. The cylinder on the left has a weight (force) on 1 pound acting downward on the piston, which lowers the fluid 10 inches. As a result of this force, the piston on the right lifts a 10 pound weight a distance of 1 inch.

The 1 pound load on the 1 square inch area causes an increase in pressure on the fluid in the system. This pressure is distributed equally throughout and acts on every square inch of the 10 square inch area of the large piston. As a result, the larger piston lifts up a 10 pound weight. The larger the cross-section area of the second piston, the larger the mechanical advantage, and the more weight it lifts.

The formulas that relate to this are shown below:

P1 = P2 (since the pressures are equal throughout).

Since pressure equals force per unit area, then it follows that

F1/A1 = F2/A2

It can be shown by substitution that the values shown above are correct,

1 pound / 1 square inches = 10 pounds / 10 square inches

Because the volume of fluid pushed down on the left side equals the volume of fluid that is lifted up on the right side, the following formula is also true.

V1 = V2

by substitution,

A1 D1 = A2 D2

• A = cross sectional area
  
• D = the distance moved
  

or

A1/A2= D2/D1

This system can be thought of as a simple machine (lever), since force is multiplied.The mechanical advantage can be found by rearranging terms in the above equation to

Mechanical Advantage(IMA) = D1/D2 = A2/A1

For the sample problem above, the IMA would be 10:1 (10 inches/ 1 inch or 10 square inches / 1 square inch).

Given these simple formulas, try to answer the questions below.

Exercises:

1. A hydraulic press has an input cylinder 1 inch in diameter and an output cylinder 6 inches in diameter.
   
   1. 
      
   2. Assuming 100% efficiency, find the force exerted by the output piston when a force of 10 pounds is applied to the input piston.
      (answer)
      
   3. If the input piston is moved through 4 inches, how far is the output piston moved?
      (answer)
      [*]A hydraulic system is said to have a mechanical advantage of 40. Mechanical advantage (MA) is FR (output) / FE (input). If the input piston, with a 12 inch radius, has a force of 65 pounds pushing downward a distance of 20 inches, find

1. the volume of fluid that has been displaced
   (answer)
   
2. the upward force on the output piston
   (answer)
   
3. the radius of the output piston
   (answer)
   
4. the distance the output piston moves
   (answer)
   

[*]What pressure does a 130 pound woman exert on the floor when she balances on one of her heels? Her heels have an average radius of 0.5 inch.

(answer)

[*]A car has a weight of 2500 pounds and rests on four tires, each having a surface area of contact with the ground of 14 square inches. What is the pressure the ground experiences beneath the tires that is due to the car?

(answer)

Extension :

[*]The input and output pistons of a hydraulic jack are respectively 1 cm and 4 cm in diameter. A lever with a mechanical advantage of 6 is used to apply force to the input piston. How much mass can the jack lift if a force of 180 N is applied to the lever and efficiency is 80%?

(answer)

[wallfish 17,020]

Buy a set of plans from PF engineering and get it right the first time with a proven design. His plans will include a bill of materials, what hydraulic components to buy and where to get them. You will find, if you build it, that the cost of the plans is minimal and well worth it. They will answer all of your questions and save you plenty of time.

[stevebo-(Moderator) 8,331]

Matt,

IMO you will NEVER be able to lift 1000lbs with a 520 (or should never attempt to). The 520 is too light of a tractor. Figure on adding a weight box to the back to offset the weight of the loader. If you pick up 300-400 lbs that is what you can do without making it dangerous. One word of advise is to try and keep the loader as close to the front of the tractor (shorter arms) and you will be able to lift a bit more. If/when you are serious and want more info my buddy may be willing to share some information with you. He is very sharp and has fabricated several custom loaders. He tends to stay away from the 520's due to the size and overall weight. When he looks for a wheel horse to put a loader on it is a D series.

I still think you should just suck it up and go buy a terramite !! :hide:

[littleredrider 409]

I agree, 1000 pounds is a bit much. I have a friend that has a JD425 with a loader, it can't pick that. Also, made a delivery and the guy took it off with a bigger JD, can't remember the size, but I'd say big for a compact, and it had a hard time picking little less than a 1000. He had a backhoe on the back, had to extend it all the way out for leverage so it wouldn't tip forward.

I spend the $50 on the plans from PF, they tell you pretty much everything you need to build one. Buddy is supposedly getting me the metal, then just need to get the hydro stuff.