hydraulic cylinder size for b7100 lift

[Leejohn]

JJ said it takes a 2" bore X 30" 4.9 sec to go out, would 2 cyl. take 9.8 sec or does that change being 2 Cyl? Are you using 2 cyl. for the lift?

 

[J_J]

Let me answer that. Yes, the time will be 9.8 sec, because speed of the cylinders is based on the GPM's. If you use two cylinders, the ips will change and therefore the extension and retraction times will change I believe Brad is going to use 24 in cyl, so the times will change. All 2 in bore cylinders will have the same ips force using the same GPM. You divide the ips into the cyl stroke to get the time of the retraction, and extension, in sec.

ips = inches per second

 

[ohiokubota]

J J is right i am going to be using two 2x30x1.125 cylinders. if they r to slow for me then i will down size to a 1.75 bore but till then i am expecting a whole lot of lift out of those cylinders. But thanks J J for talking to me today on the phone the info was really interesting and will be consider into the plan of motion.

 

[jas67]

a 2 in bore, and 1.125 shaft, at 5 GPM, would have an extend speed of 6.1 ipsx30 = 4.9 sec
-----------------------------------------------------retract speed of 9 ipsx30 = 3.3 sec
__________________

Push force on that cylinder would be 7,854 lbs
pull force---------------------------5,369
push at a 45 degree angle----------5,554
pull--------------------------------3,796

all the above data , figured at 2500 psi, and 5 GPM

The B7100's hydraulic system is 1700 PSI, and 3 GPM, and there are TWO lift cylinders, so:

extend, 1.8 IPS, 16.7 seconds, 5341 lbs
retract, 2.7 IPS, 11.1 seconds, 3651 lbs

The above force is PER CYLINDER. So, double that before you go through all your lever math.

I would be inclined to use 1.5" cylinders which would still give plenty of force, and be faster.

Raise time for the LA304 on a B2320 is about 3 seconds (no load), so 16.7 seconds will seem like an eternity.

You might even want to use a shorter lift cylinder (like maybe 24") and just position your pivots accordingly. You'll still have way more force than needed.

 

[J_J]

What I posted was on an assumption, just for reference. Here is the data for a 1.5 with a 1 in shaft, at 3 GPM. @ 1700 psi

push 3004 lbs
pull 1669 lbs

cyl at 45 degree angle

push 2124 lbs push force at end of cylinder
pull 1180 lbs

entend time 6.5 ips 30 in cyl = 4.6 sec
retract tme 11.8 ips = 2.5 sec

Double the time for two cyl

 

[Egon]

The B7100's hydraulic system is 1700 PSI, and 3 GPM,

What units are kubota's pump rate in?

 

[ohiokubota]

lets see i think a 2x24 cylinder is a hair to big but i thought about buying a 1.75X23.12X1.06
* Double acting
* Bore x Stroke 1-3/4" X 23-1/8"
* PSI Max. 3,000
* Rod Dia. 1-1/16"
* Ports SAE 6
* Retracted length 32-11/16"
I think the 2x24 should be alright tho