hydraulic hose and coupling sizes ???

3/4 was used, but smaller might work just fine depending on the volume of your cylinders, and if you need the fastest speed your tractor can produce. Start by figuring out if the lower pressure available can lift the implement weight with the smaller cylinders that were designed for higher pressure & lower volume.

yes i still have some hydraulic cylinders left from when we farmed with low pressure john deere tractors. pretty sure if the old 830 would lift the disk then the D4 should too?
do you think the smaller hoses would affect the speed to much? i need to look but i think the old deere used 1/2 inch hoses but the cyl diameter was quite large.

yes i still have some hydraulic cylinders left from when we farmed with low pressure john deere tractors. pretty sure if the old 830 would lift the disk then the D4 should too?
do you think the smaller hoses would affect the speed to much? i need to look but i think the old deere used 1/2 inch hoses but the cyl diameter was quite large.

[quote="bursitis"]yes i still have some hydraulic cylinders left from when we farmed with low pressure john deere tractors. pretty sure if the old 830 would lift the disk then the D4 should too?
do you think the smaller hoses would affect the speed to much? i need to look but i think the old deere used 1/2 inch hoses but the cyl diameter was quite large.[/quote]

I think John Deere upped the operating pressure when they went from A,B series to 50,60 series in anticipation of the "New" 20 series design? I know the A,B series had the gear pump in the rockshaft housing where as the 50,60 series had a "live" vane pump mounted on the transmission case just under the Console. (Pretty Sure)

the john deere i was referring to was a 1957 i think 820. two cyl johnny popper with low pressure hydraulics. we had to use large diameter cylinders to lift some equipment.

Higher pressure means the fluid runs faster, lower pressure means the fluid runs slower. Larger hoses means more fluid can be pushed through, smaller hoses means less fluid can be pushed through.

Hose size doesn't really matter as far as pressure. You can use the biggest hose you can find if you want, it just may take longer to reach the pressure you need do to the hose needing to fill up with fluid. You could also use the tiniest hose you can find as long as the pressure output can overcome the back pressure of the hydraulic cylinder.

A small hose with high pressure may make fine adjustments possible, but may also mean slow cylinder speed.

Higher pressure increases cylinder speed, and more volume would also increase cylinder speed.

I imagine there is some mathematical formula to determine the number of gallons of fluid that can be pumped through a given hose diameter at a given pressure that could tell you how long it would take to fill a lift cylinder.

However, It may not be a smart idea to use smaller hoses on a hydraulic pump designed for bigger hoses. You may strain the pump and break it because it would have to push the same volume of liquid through a smaller hose. Meaning higher pressure.

Anyways, basically you cannot go wrong with bigger hoses as long as the bigger hoses can handle the pressure and as long as you have enough fluid storage capacity to fill those hoses.

Higher pressure means the fluid runs faster, lower pressure means the fluid runs slower. Larger hoses means more fluid can be pushed through, smaller hoses means less fluid can be pushed through.

Hose size doesn't really matter as far as pressure. You can use the biggest hose you can find if you want, it just may take longer to reach the pressure you need do to the hose needing to fill up with fluid. You could also use the tiniest hose you can find as long as the pressure output can overcome the back pressure of the hydraulic cylinder.

A small hose with high pressure may make fine adjustments possible, but may also mean slow cylinder speed.

Higher pressure increases cylinder speed, and more volume would also increase cylinder speed.

I imagine there is some mathematical formula to determine the number of gallons of fluid that can be pumped through a given hose diameter at a given pressure that could tell you how long it would take to fill a lift cylinder.

However, It may not be a smart idea to use smaller hoses on a hydraulic pump designed for bigger hoses. You may strain the pump and break it because it would have to push the same volume of liquid through a smaller hose. Meaning higher pressure.

Anyways, basically you cannot go wrong with bigger hoses as long as the bigger hoses can handle the pressure and as long as you have enough fluid storage capacity to fill those hoses.

[quote="BigAgCat"]Higher pressure means the fluid runs faster, lower pressure means the fluid runs slower. Larger hoses means more fluid can be pushed through, smaller hoses means less fluid can be pushed through.
[/quote]
Not entirely true. Higher pressure means you can move more with the same size cylinder. The velocity of the oil will depend on the hose size and pump flow rate. If you have a hose that can handle 50gpm and no resistance at the end of the hose then you will get the same oil speed using a 6000psi 10gpm pump as you will with a 1000psi 10gpm pump.
[quote]
Hose size doesn't really matter as far as pressure. You can use the biggest hose you can find if you want, it just may take longer to reach the pressure you need do to the hose needing to fill up with fluid. You could also use the tiniest hose you can find as long as the pressure output can overcome the back pressure of the hydraulic cylinder.
[/quote]
Most hydraulic systems, once filled with oil don't allow that oil to escape except for the valve return to tank. Both the rod and piston end of the cylinder will be filled with oil and will not lose that oil under normal operation except when using the float function and that loss will be minimal. If the hose is full of oil and you pump 5 gallons in one end then 5 gallons will come out the other end no matter the size of the hose.
[quote]
A small hose with high pressure may make fine adjustments possible, but may also mean slow cylinder speed.
[/quote]
And much higher velocity of oil. The reason the hose is controlling the speed of the cylinder is due to a restriction in flow not pressure.
[quote]
Higher pressure increases cylinder speed, and more volume would also increase cylinder speed.
[/quote]
Higher pressure does not increase cylinder speed only flow rate increases cylinder speed. They are however both related. For example if you want to lift a certain weight at a certain speed and you calculate you need a given flow rate and pressure to lift the weight and then you double the load but still want the same speed then the flow rate will be the same but the pressure will increase due to the extra resistance.
[quote]
I imagine there is some mathematical formula to determine the number of gallons of fluid that can be pumped through a given hose diameter at a given pressure that could tell you how long it would take to fill a lift cylinder.
[/quote]
Yes there is a formula. I think there are a few online calculators that you can use but you need all the info such as pump and valve displacement at a given engine speed, required cylinder speeds and sizes, whether you want the speeds to be the same for extension and retract etc
[quote]
However, It may not be a smart idea to use smaller hoses on a hydraulic pump designed for bigger hoses. You may strain the pump and break it because it would have to push the same volume of liquid through a smaller hose. Meaning higher pressure.
[/quote]
That's why hydraulic systems have relief valves. The pressure in the pump, valves, cylinders and hoses should not exceed the maximum pressure the relief is set to. Modern valving allows different pressures for each function in addition to the main relief.
[quote]
Anyways, basically you cannot go wrong with bigger hoses as long as the bigger hoses can handle the pressure and as long as you have enough fluid storage capacity to fill those hoses.
[/quote]
Hyd hose is expensive and the bigger you go the more you will pay. I can understand wanting to keep the hoses small. Also smaller hoses are more flexible and require less wires for the same pressure.

[quote="BigAgCat"]Higher pressure means the fluid runs faster, lower pressure means the fluid runs slower. Larger hoses means more fluid can be pushed through, smaller hoses means less fluid can be pushed through.
[/quote]
Not entirely true. Higher pressure means you can move more with the same size cylinder. The velocity of the oil will depend on the hose size and pump flow rate. If you have a hose that can handle 50gpm and no resistance at the end of the hose then you will get the same oil speed using a 6000psi 10gpm pump as you will with a 1000psi 10gpm pump.
[quote]
Hose size doesn't really matter as far as pressure. You can use the biggest hose you can find if you want, it just may take longer to reach the pressure you need do to the hose needing to fill up with fluid. You could also use the tiniest hose you can find as long as the pressure output can overcome the back pressure of the hydraulic cylinder.
[/quote]
Most hydraulic systems, once filled with oil don't allow that oil to escape except for the valve return to tank. Both the rod and piston end of the cylinder will be filled with oil and will not lose that oil under normal operation except when using the float function and that loss will be minimal. If the hose is full of oil and you pump 5 gallons in one end then 5 gallons will come out the other end no matter the size of the hose.
[quote]
A small hose with high pressure may make fine adjustments possible, but may also mean slow cylinder speed.
[/quote]
And much higher velocity of oil. The reason the hose is controlling the speed of the cylinder is due to a restriction in flow not pressure.
[quote]
Higher pressure increases cylinder speed, and more volume would also increase cylinder speed.
[/quote]
Higher pressure does not increase cylinder speed only flow rate increases cylinder speed. They are however both related. For example if you want to lift a certain weight at a certain speed and you calculate you need a given flow rate and pressure to lift the weight and then you double the load but still want the same speed then the flow rate will be the same but the pressure will increase due to the extra resistance.
[quote]
I imagine there is some mathematical formula to determine the number of gallons of fluid that can be pumped through a given hose diameter at a given pressure that could tell you how long it would take to fill a lift cylinder.
[/quote]
Yes there is a formula. I think there are a few online calculators that you can use but you need all the info such as pump and valve displacement at a given engine speed, required cylinder speeds and sizes, whether you want the speeds to be the same for extension and retract etc
[quote]
However, It may not be a smart idea to use smaller hoses on a hydraulic pump designed for bigger hoses. You may strain the pump and break it because it would have to push the same volume of liquid through a smaller hose. Meaning higher pressure.
[/quote]
That's why hydraulic systems have relief valves. The pressure in the pump, valves, cylinders and hoses should not exceed the maximum pressure the relief is set to. Modern valving allows different pressures for each function in addition to the main relief.
[quote]
Anyways, basically you cannot go wrong with bigger hoses as long as the bigger hoses can handle the pressure and as long as you have enough fluid storage capacity to fill those hoses.
[/quote]
Hyd hose is expensive and the bigger you go the more you will pay. I can understand wanting to keep the hoses small. Also smaller hoses are more flexible and require less wires for the same pressure.