hydraulic actuator

Question 1

two main types of single acting cylinders

Answer 1

piston and ram

Question 2

piston type cylinders

Answer 2

consists of a piston and a rod that slides up and down the barrel . piston seal rings on the piston center it and act as a wear surface

Question 3

what could cause a differential cylinder to drift while in the hold position

Answer 3

leaking piston seals

Question 4

most common cause of cavitation failure in a hydraulic motor

Answer 4

when the motor rotates faster then the the pump can provide oil

Question 5

cylinder cushions

Answer 5

are used to slow down the hydraulically operated implement by restricting the rate of return oil and creating a back pressure that resist piston movement

Question 6

ram type cylinders

Answer 6

simpler and more commonly used consists of a piston that slides within a cylinder barrel .

Question 7

the amount of torque a motor can produce depends on

Answer 7

motor inlet pressure and motor displacement

Question 8

why can a piston motors swash plate never reach a perpendicular position

Answer 8

because the motor would become hydrostatically locked . plate angle is limited to 6.5 to 19 degrees from perpendicular

Question 9

under a constant flow rate what is the relationship between speed and displacement

Answer 9

if speed increases . motor displacement decreases

Question 10

if you suspect the piston seals of a cylinder are leaking you should

Answer 10

measure the amount of return oil while the cylinder is being stalled

Question 11

most common use for cylinder reliefs

Answer 11

used on systems that have limited reservoir capacity witch would limit cooling capacity of the system

Question 12

double acting single rod cylinders are often referred to as

Answer 12

differential cylinders . because of the difference of retraction vs extension speed and force

Question 13

force and speed of cylinder movement changes depending upon

Answer 13

what stage is moving . first stage being the largest has the most force but moves the slowest . each successive stage force is decreased and speed is increased

Question 14

what is the difference in vane construction from a pump to a motor

Answer 14

vane motors rely on spring pressure to keep the vanes against the cam ring during start up

Question 15

double acting cylinders

Answer 15

are both hydraulically extended and retracted

Question 16

gerotor motors

Answer 16

have low rpm high torque consist of a spool valve a gerotor star

Question 17

geroller motors

Answer 17

have low rpm and high torque have a disc valve to direct oil flow and uses rollers in the housing to assist in less internal friction of the geroller stars movement

Question 18

piston reliefs

Answer 18

allow pump oil flow to bypass the piston when it reaches the end of its stroke

Question 19

telescoping single acting cylinders

Answer 19

used to obtain additional stroke length in a compact package . constructed with two or more cylinders called stages

Question 20

double acting double rod cylinders

Answer 20

has equal volume and piston area on both sides . also known as non differential cylinder

Question 21

single acting cylinders

Answer 21

are hydraulically actuated in one direction and require some other force to cause the piston to move in the opposite direction

Question 22

piston relief valves are

Answer 22

double check valves that open when the piston reaches the end of its stroke and close when in mid range of operation

Question 23

hydraulic motor operating principles

Answer 23

converts hydraulic energy into rotary mechanical energy . by converting oil flow and pressure into speed and torque

Question 24

what are some additional cylinder features

Answer 24

quick drop . cylinder cushions . piston relief

Question 25

how are dirt and contamination prevented from entering the cylinder

Answer 25

dirt seal on the outer end of the cylinder barrel

Question 26

when removing the rod and piston assembly from a hydraulic cylinder you should not use

Answer 26

compressed air . piston my leave the barrel assembly at extreme velocity

Question 27

what is the relationship between motor displacement and torque generation in a motor

Answer 27

torque increases proportionally to the increase of motor displacement

Question 28

how is the flow of oil directed through a ram type cylinder

Answer 28

oil flow is directed into the inlet and outlet port to extend the cylinder to retract the cylinder oil flow from the outlet/ inlet is connected to the reservoir

Question 29

quick drop valves

Answer 29

provide faster lowering cycle times on implements

Question 30

contamination failure of a motor

Answer 30

components will appear dull and sandblasted

Question 31

how dose a quick drop valve operate

Answer 31

by supplementing pump flow to the base of the cylinder by redirecting rod end return flow to the base end known as regeneration through the use of a spool valve and spring loaded plunger