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Flashcards in Lab Deck (22)
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1

four methods of energy transmission

mechanical (drive shaft), electrical (motor), hydraulics (crushing car), pneumatics (air tools)

2

who first defined the fundamental law of hydraulic system

Pascal

3

what fluid was used in the earliest hydraulic system and why

water - plentiful and easy to get

4

what type of fluid is now used in hydraulic systems and why?

oil

5

5 modern applications of hydraulic power transmission

landing gear, construction equipment, scissor lift, cranes, plows, presses, etc.

6

pressure in a hydraulic system

created by the resistance of the system (pressure=resistance)

7

resistance

caused by friction, diameter of hose, viscosity of fluid (temp.), length of hose, number of fittings, load, directional control valve (pressure drop)

8

relief valve

safety device - sets the highest pressure so that way no components get damaged

9

flow

describes the movement of gases, any fluid that can flow can transmit power

10

velocity and friction

when velocity increases, friction decreases

11

minimize frictional losses

increase pipe diameter, reduce the surface toughness, minimize length of piping

12

flow control valve

-operate by offering a restriction or partial blockage in a line (manual variation of the size of an orifice)
-flow through orifice depends on size of orifice, pressure differential across orifice, & temperature

13

3 types of valves

directional control valve, flow control valve, and pressure control valve

14

check valve

allows fluid to flow in one direction

15

working relationship

there is a working relationship between flow control valve and simple relief valve

16

meter in

controlling flow rate into cylinder, control extension speed, restricts amount of fluid going into the cylinder

17

meter out

controls the flow rate out of the cylinder so it controls extension speed in a backwards way, cylinder is prevented from overrunning, maintains constant back pressure, important for drilling applications

18

bleed off circuit

flow to cylinder is regulated by sending some of the pump flow to the tank, more efficient than meter in/meter out

19

rapid traverse circuit/feed circuit

extends quickly (rapid traverse) until the cam button is pushed and then it extends slower (feed), only extension is affected

20

cracking pressure

when a check valve reaches cracking pressure, it will open

21

isothermal

stays at the same temperature

22

pilot operated check valve

although it only allows flow in one direction, if there is enough pressure from the pilot line, the no flow direction can be made into flow