Lab

Question 1

four methods of energy transmission

Answer 1

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

Question 2

who first defined the fundamental law of hydraulic system

Answer 2

Pascal

Question 3

what fluid was used in the earliest hydraulic system and why

Answer 3

water - plentiful and easy to get

Question 4

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

Answer 4

oil

Question 5

5 modern applications of hydraulic power transmission

Answer 5

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

Question 6

pressure in a hydraulic system

Answer 6

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

Question 7

resistance

Answer 7

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

Question 8

relief valve

Answer 8

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

Question 9

flow

Answer 9

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

Question 10

velocity and friction

Answer 10

when velocity increases, friction decreases

Question 11

minimize frictional losses

Answer 11

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

Question 12

flow control valve

Answer 12

• 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

Question 13

3 types of valves

Answer 13

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

Question 14

check valve

Answer 14

allows fluid to flow in one direction

Question 15

working relationship

Answer 15

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

Question 16

meter in

Answer 16

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

Question 17

meter out

Answer 17

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

Question 18

bleed off circuit

Answer 18

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

Question 19

rapid traverse circuit/feed circuit

Answer 19

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

Question 20

cracking pressure

Answer 20

when a check valve reaches cracking pressure, it will open

Question 21

isothermal

Answer 21

stays at the same temperature

Question 22

pilot operated check valve

Answer 22

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