three techniques to synchronize two cylinders
- orifice type flow divider
- gear type flow divider
- mechanical coupling
orifice type flow divider
- two orifices on either side of divider can be adjusted
- same flow and same size cylinders means they will extend at the same time
gear type flow divider
- functions like two gear motors with their shafts rigidly attached
- potential problem: pressure intensification
mechanical coupling
the beam (load) slides in a track on both sides and will bind the track if one cylinder gets ahead of the other
key principle in design
Sometimes, the problem can be better solved with a modification to the functional requirement rather than a modification to the hydraulic circuit.
cushioning
- reduces cylinder’s velocity before it strikes the end cap
- protects end covers of cylinders
mounting method of cylinders and loads
- rods are not designed to take a side load
- column loading
pilot operated check valve
operates like a normal check valve in the flow direction but will open and allow flow through other direction if the pressure from the pilot line is high enough
types of cylinders
- double acting
- single acting, spring return
- double rod
- tandem
- telescoping
telescoping cylinder
used when a long stroke is needed and the space available to mount the cylinder is limited
agricultural grade cylinder
good for applications where annual use is limited
industrial grade cylinder
good for manufacturing applications when cylinders cylinder 1000 times or more a year
key features of cylinder
- seals
- rod wiper
- rod bearing to help support the rod
several factors interact to produce a given load acceleration
- valve dynamics
- oil compressibility
- line compliance
- relief valve performance
- pump volumetric efficiency
- leakage (in DCV and past cylinder seals)
