hydraulic system types

Question 1

what is the definition of a hydraulic system

Answer 1

all of the interconnected components mounted on a vehicle or piece of equipment

Question 2

what is a hydraulic circuit

Answer 2

a group of interconnected components within a hydraulic system that perform a specific function

Question 3

what is an open center hydraulic system

Answer 3

one that allows pump flow to return to the reservoir when the directional control valve in in the neutral position

Question 4

another name for a open center hydraulic system with fixed displacement pump is

Answer 4

constant flow

Question 5

what type of equipment would use the constant flow type hydraulic system

Answer 5

wheel loader

Question 6

another name for open center hydraulic system with pressure compensated pump

Answer 6

constant horse power

Question 7

how dose a constant horsepower type hydraulic system work

Answer 7

destroke the pump as pressure rises to limit maximum power that the pump can draw from the engine

Question 8

closed center hydraulic systems are often called

Answer 8

demand type or load sensing

Question 9

what are the advantages of load sensing hydraulic systems

Answer 9

provide minimum wasted energy . precise control of actuator motion

Question 10

what is margin pressure

Answer 10

the pumps outlet pressure is kept slightly higher than the actuator load pressure ( 150 to 450 ) psi

Question 11

what would use the closed center load sensing hydraulic system

Answer 11

dozer

Question 12

HST stands for

Answer 12

hydrostatic transmission

Question 13

what are the four basic hydrostatic configurations

Answer 13

open circuit ( loop ) with fixed displacement or variable displacement pumps and closed circuit ( loop ) with fixed or variable displacement pumps

Question 14

what is the most common type of HST system used

Answer 14

closed loop with variable displacement reversible pump

Question 15

what would use the hydrostatic transmission system

Answer 15

compactor

Question 16

when pumps are connected front to back what pump is the driven pump and what pump is the idler

Answer 16

the pump connected to the engine is the driven and the rear pump is the idler

Question 17

power shift pressure has what effect on the main hydraulic pump

Answer 17

as power shift pressure decreases pump output increases. as power shift pressure increases pump output decreases

Question 18

open center hydraulic systems are most often used

Answer 18

when the hydraulic operations are not a high percentage of the machines duty cycle

Question 19

constant hoarse power open center hydraulic systems maintain a constant power draw from the engine by varying

Answer 19

pump displacement proportional to the load on the system

Question 20

the identifying characteristics of a closed center hydraulic system is

Answer 20

the directional control valve always blocks pump oil flow in neutral position

Question 21

why are closed center systems equipped with pressure compensated pumps often called demand type systems

Answer 21

because flow is only provided when there is work to preform

Question 22

the most commonly used HST in mobile heavy equipment is

Answer 22

closed circuit system with a variable displacement reversible pump