Backhoe Trench Master Backhoe.

[MJPetersen]

If you take the outside circumference of the cylinder divided by 3.14 will give you the outside diameter, minus 3/8-1/2 inches will give the inside cylinder diameter; The stroke can be approximated from the length of the barrel cylinder minus the piston length. The volume of the cylinder then is the area of the cylinder = 3.14 x 1/2 x diamerter x stroke. The figure that you will have will be cubic inches. So divide that figure be 231 and you will have the volume in gallons. divide that by 4.5 and then multiply by 60 and you will know how long it will take to extend that cylinder at full volume flow.

For example a 2 in cylinder with a stroke of 16 inches. 1/2 x 2 x 3.14 = 3.14 square inches. 3.14 x 16 = 50.24 cubic inches. So that divided by 231 = .22 gallons. That is a bit under a quart. Therefore, theoretically your tractor could extend that cylinder in about 3 seconds.

If your tractor is chinese the cylinders are probably metric. Cylinders are standard sizes 2 in, 2.25, 2.5, 3.inches. Metrics are normally by 10 mm. 40, 50, 60mm. 50 mm is approx 2 inches.

Maybe that will help you to figure if a pump is necessary.

Mike

 

[wedge40]

If you take the outside circumference of the cylinder divided by 3.14 will give you the outside diameter, minus 3/8-1/2 inches will give the inside cylinder diameter; The stroke can be approximated from the length of the barrel cylinder minus the piston length. The volume of the cylinder then is the area of the cylinder = 3.14 x 1/2 x diamerter x stroke. The figure that you will have will be cubic inches. So divide that figure be 231 and you will have the volume in gallons. divide that by 4.5 and then multiply by 60 and you will know how long it will take to extend that cylinder at full volume flow.

For example a 2 in cylinder with a stroke of 16 inches. 1/2 x 2 x 3.14 = 3.14 square inches. 3.14 x 16 = 50.24 cubic inches. So that divided by 231 = .22 gallons. That is a bit under a quart. Therefore, theoretically your tractor could extend that cylinder in about 3 seconds.

If your tractor is chinese the cylinders are probably metric. Cylinders are standard sizes 2 in, 2.25, 2.5, 3.inches. Metrics are normally by 10 mm. 40, 50, 60mm. 50 mm is approx 2 inches.

Maybe that will help you to figure if a pump is necessary.

Mike

Mike I went outside and just measured the cylinder diameter and it was 2.9" So as an estimate I would say I have 2.5" cylinders. I'm assuming that bigger the cylinder the more powerfull the hydraulics? Or is it a combination of both the cylinder size and the stroke.

Wedge

 

[MJPetersen]

2.5 would be about right for that size of hoe. You are right that the bigger the cylinder the more power, given the same system hyd pressure. Power is a combination of diameter of cylinder and the pressure. In your situation then the surface of the piston (not the rod side) is 4.9 sq inches. OK say you have a system pressure of 2000 psi then the force that you can generate on that piston is 9,800 lbs of push. If your stroke is 16 inches the volume of the cylinder is 78.4 cubic inches--or .34 gal--about a third of a gallon. Given that your system has the capacity of 4.5 gpm then theoretically it would take 4.5 seconds to fully extend that cylinder.

If it were mine, I believe that I would hook it up to the existing hyd and see how it performed. If I deemed it too slow then I would go through the process of adapting the pump. Just my opinion.

Mike

 

[Mgrove]

HI
If you don't plan on making a living with the hoe, it should perform ok depending on your use. I noticed that it has eye bolts in the dipper arm, thats common on the Chinese hoes. I just purchased a Woods 7500 off EBAY, the pump was split, hoping I can run it with the hydraulics from the Jinma 454 $2200. Makes me wonder if I got a good buy or not. It seems funny, I can buy a 20hp Jinma tractor for about the same price as a (quality) hoe. It just seems like we are getting ripped off!

 

[wedge40]

HI
If you don't plan on making a living with the hoe, it should perform ok depending on your use. I noticed that it has eye bolts in the dipper arm, thats common on the Chinese hoes. I just purchased a Woods 7500 off EBAY, the pump was split, hoping I can run it with the hydraulics from the Jinma 454 $2200. Makes me wonder if I got a good buy or not. It seems funny, I can buy a 20hp Jinma tractor for about the same price as a (quality) hoe. It just seems like we are getting ripped off!

Welcome aboard Mgrove.

Believe it or not $2200 for a Woods is a steal. Even if it does need a little TLC. I used mine some and then had a seal blow on the pump. Since its Chinese its going to be a bear to find parts every time it breaks. I got it fixed (I think) but never took the time put it all back together to check it out. On the other hand, your Wood BH has all standard connections. If/when it breaks, you can go to any hydraulic shop and get parts. I'm learning the hard that that is worth a lot of extra money up front.

Wedge