clawmute
ArboristSite Operative
Here is some handy hydraulic data which I often use. These are "rules of thumb, etc.
1. a gallon is equal to 231 cubic inches. Sometimes it is handy to convert flows/volumes into cubic inches.
2. 1hp input is required for each 1gpm @1500psi. This is good for rough estimating the approx. hp rating of an engine or motor for driving a pump.
for example, a 5gpm pump operating at 1500 psi needs a 5hp motor, or at 300psi a 10hp motor.
3. It takes about 5% of the full rated hp to idle an unloaded pump.
4. The secret to a long lived hydraulic system is clean oil. Keeping the filter(s) changed will add life to the system.
5. One of the most common problems encountered is cavitation of a hydraulic pump inlet due to dirt buildup on the suction strainer. Higher pump noise & system heat output are usually indicators that something is not right.
6. Increasing a cylinder size using the same pump will result in slower extend/retract cycle times.
7. Decreasing a cylinder size using the same pump will result in faster extend/retract cycle times.
8. Hydraulic cylinder speed; S = CIM/A where S = speed in inches per minute,
CIM is oil flow into the cylinder in cu. in./min., A is the piston area in square inches.
9. Hydraulic cylinder retract speed is similar only the rod dia. must be subtracted from the piston area; RS = CIM/(A-ra) where RS is retract speed in inches/min., CIM is oil flow into the cylinder in cu. in/min., A is the piston area in sq. inches, and ra is the area of the rod cross section in square inches.
Misc. input horse powers @ given gpm
GPM________1000psi_______1500psi_______2000psi_______3000psi
5-------------3.43 --------- 5.15 ---------- 6.86----------10.3
10 -----------6.86----------10.3------------13.7-----------20.6
15------------10.3----------15.4------------20.6-----------30.9
20------------13.7----------20.6 -----------27.5-----------41.2
25------------17.2----------25.7------------34.3-----------51.5
Hydraulic Cylinder speeds (inches per minute)
These are the "extend" speeds. The retract speeds will be greater since you have the same oil flow against a smaller area (piston area less rod dia. area)
Piston Dia.______ 5gpm_______8gpm______12gpm______20gpm
3.25"---------------139---------223----------332---------556
4" ------------------92----------147---------220---------368
5" ------------------59---------- 94----------140---------235
6" ------------------41----------65----------- 96---------163
If you are thinking about building a hydraulic splitter, you might consider having a cylinder made to suit your purposes. There is a small hydraulics mfgr in our area that can make any cylinder you want with mounting and rod end conditions to suit your setup. Most likely there is probably one near you, or you can even pick up a used one from a scrap equipment dealer and refurbish it with new seals/packing.
You can have a hefty oversize rod made since the retract power required will be considerably less that the extend.
Below is a picture of 5 press roll machines I've been designing that are used to crush wood. Each uses 2 - 8" dia hydraulic cylinders and is lifting a vaned roll assembly that weighs about 6tons. The rods on these cylinders are 4" in diameter. Both rolls are also driveshaft driven with a 50hp motor on each. Since there are two cylinders per roll, a pair of linear transducers are used to keep the roll level and to control the flow of oil into and out of the cylinders.
1. a gallon is equal to 231 cubic inches. Sometimes it is handy to convert flows/volumes into cubic inches.
2. 1hp input is required for each 1gpm @1500psi. This is good for rough estimating the approx. hp rating of an engine or motor for driving a pump.
for example, a 5gpm pump operating at 1500 psi needs a 5hp motor, or at 300psi a 10hp motor.
3. It takes about 5% of the full rated hp to idle an unloaded pump.
4. The secret to a long lived hydraulic system is clean oil. Keeping the filter(s) changed will add life to the system.
5. One of the most common problems encountered is cavitation of a hydraulic pump inlet due to dirt buildup on the suction strainer. Higher pump noise & system heat output are usually indicators that something is not right.
6. Increasing a cylinder size using the same pump will result in slower extend/retract cycle times.
7. Decreasing a cylinder size using the same pump will result in faster extend/retract cycle times.
8. Hydraulic cylinder speed; S = CIM/A where S = speed in inches per minute,
CIM is oil flow into the cylinder in cu. in./min., A is the piston area in square inches.
9. Hydraulic cylinder retract speed is similar only the rod dia. must be subtracted from the piston area; RS = CIM/(A-ra) where RS is retract speed in inches/min., CIM is oil flow into the cylinder in cu. in/min., A is the piston area in sq. inches, and ra is the area of the rod cross section in square inches.
Misc. input horse powers @ given gpm
GPM________1000psi_______1500psi_______2000psi_______3000psi
5-------------3.43 --------- 5.15 ---------- 6.86----------10.3
10 -----------6.86----------10.3------------13.7-----------20.6
15------------10.3----------15.4------------20.6-----------30.9
20------------13.7----------20.6 -----------27.5-----------41.2
25------------17.2----------25.7------------34.3-----------51.5
Hydraulic Cylinder speeds (inches per minute)
These are the "extend" speeds. The retract speeds will be greater since you have the same oil flow against a smaller area (piston area less rod dia. area)
Piston Dia.______ 5gpm_______8gpm______12gpm______20gpm
3.25"---------------139---------223----------332---------556
4" ------------------92----------147---------220---------368
5" ------------------59---------- 94----------140---------235
6" ------------------41----------65----------- 96---------163
If you are thinking about building a hydraulic splitter, you might consider having a cylinder made to suit your purposes. There is a small hydraulics mfgr in our area that can make any cylinder you want with mounting and rod end conditions to suit your setup. Most likely there is probably one near you, or you can even pick up a used one from a scrap equipment dealer and refurbish it with new seals/packing.
You can have a hefty oversize rod made since the retract power required will be considerably less that the extend.
Below is a picture of 5 press roll machines I've been designing that are used to crush wood. Each uses 2 - 8" dia hydraulic cylinders and is lifting a vaned roll assembly that weighs about 6tons. The rods on these cylinders are 4" in diameter. Both rolls are also driveshaft driven with a 50hp motor on each. Since there are two cylinders per roll, a pair of linear transducers are used to keep the roll level and to control the flow of oil into and out of the cylinders.