Work Function System Fundamentals Training

IHA Dresden

1| IHA Dresden Internationale Hydraulik Akademie GmbH

Am Promigberg 26, D- 01108 Dresden
Load control
IHA

Internationale Hydraulik Akademie GmbH

Am Promigberg 26, D- 01108 Dresden
 Load Control

100
Negative Load 100

Negative Load

3| IHA Dresden
 Throttles
100 100
200 200

0 0

2 :1
Meter out throttle

Only for one load and the

same velocity 100
200

100
A B
bar
P T

250 bar

4| IHA Dresden
 Throttles
100 100
200 200

0 0

2 :1
A higher load results a
higher velocity with the
same settings
100
200

200
A B
bar
P T

250 bar

5| IHA Dresden
 Throttles
100 100
200 200

0 0
Meter in throttle closed

closed

100
200
control only with meter
out throttle 0

100
Vacuum ! A B
bar
P T

250 bar

6| IHA Dresden
 Throttles
100 100
200 200

0 0

Meter out throttle closed

2 :1
100
200
Pressure intensification! closed
0

100
A B
bar
P T

250 bar

7| IHA Dresden
 Counter balance
100 100
200 200

Velocity control with 0 0

meter in throttle

Counterbalance valve

2 :1
100
200

0
For only one load and
various velocities
200
220bar

A B

P T

positive
250 bar pressure for
lowering
5-10 bar

8| IHA Dresden
 Counter balance
100 100
200 200

Velocity control with 0 0

meter in throttle

2 :1
50% closed

Counterbalance valve
100
200

0
For only one load and
various velocities
200
220bar

A B

P T

250 bar

9| IHA Dresden
 Counter balance
100 100
200 200

velocity control with 0 0

meter in throttle

75% open

Counterbalance valve

2 :1
100
200

0
For only one load and
various velocities 220bar 0

A B

P T

Higher pressure
250 bar for lowering

10 | IHA Dresden
 Counter balance pPilot= (200-0):(3+2)= 40 bar

100 100
200 200

0 0
Releasable
counterbalance valve

2 :1
75% open

X= pilot ratio
pS= pressure setting X= 3 100  =2
200
pL= load pressure
pPilot= pilot pressure
0
= cylinder ratio
pS= 200bar 0 pL
Pilot pressure
(pS-pL):(X+)= pPilot A B

P T

For various loads and

velocities

11 | IHA Dresden
 Counter balance
pPilot= (200-100):(3+2)= 20 bar

100 100
200 200

0 0
Releasable
counterbalance valve

2 :1
75% open

X= pilot ratio
pS= pressure setting X= 3 100  =2
200
pL= load pressure
pPilot= pilot pressure
0
= cylinder ratio
pS= 200bar
Pilot pressure 100 pL

(pS-pL):(X+)= pPilot A B

P T

For various loads and

velocities

12 | IHA Dresden
 Counter balance
pPilot= (200-200):(3+2)= 0 bar

100 100
200 200

0 0
Releasable
counterbalance valve

2 :1
75% open

X= pilot ratio
pS= pressure setting X= 3 100  =2
200
pL= load pressure
pPilot= pilot pressure
0
= cylinder ratio
pS= 200bar
Pilot pressure 200 pL

(pS-pL):(X+)= pPilot A B

P T
Pressure setting is too low

13 | IHA Dresden
 Counter balance
pPilot= (260-200):(3+2)= 12 bar

100 100
200 200

0 0
Releasable
counterbalance valve

2 :1
75% open

X= pilot ratio
pS= pressure setting X= 3 100  =2
200
pL= load pressure
pPilot= pilot pressure 0
= cylinder ratio
pS=
Pilot pressure 260bar 200 pL

(pS-pL):(X+)= pPilot A B

P T

Pressure setting:
For various loads and
Highest load pressure
velocities
+30%

14 | IHA Dresden
 Counter balance pPilot= (260-200):(3+2)= 12 bar
pPilot= (270-200):(3+2)= 15 bar
100 100
200 200

0 0

2 :1
75% open

100 X= 3 100  =2
200 200

0 0

A,B throttled  T pS=

260bar 200 pL

A B +10 bar

P T

Back pressure in
250 bar return line
10 bar

15 | IHA Dresden
 Counter balance
pPilot= (260-200):(3+2)= 12 bar

100 100
200 200

0 0

2 :1
75% open

1:3

100 X= 3 100  =2
200 200

0 0

pS=
260bar 200 pL

A B

P T

Unloaded to
250 bar leakage line

16 | IHA Dresden
 Counter balance
100 100
200 200

0 0

2 :1
75% open

100 100
200 200

0 0

260bar
A B 200
P T

250 bar
Weak structure 
instable

17 | IHA Dresden
 Lowering valve
100 100
200 200

Velocity control with 0 0

meter in throttle

2 :1
75% open
Load lowering valve

100
200
Controls the meter in
pressure 0

10bar

A B 200
P T

250 bar

18 | IHA Dresden
 Lowering valve
100 100
200 200

Velocity control with 0 0

meter in throttle

2 :1
75% open
Load lowering valve

100
200
Controls the meter in
pressure 0

10bar

A B 200
P T

250 bar Spool type valve with

leakage

19 | IHA Dresden
 Lowering valve
100 100
200 200

Velocity control with 0 0

meter in throttle

2 :1
75% open

the meter in pressure

100
controls the spool 200

10bar

A B 0
P T

250 bar

20 | IHA Dresden
 Lowering valve
100 100
200 200
No vacuum!
Velocity control with 0 0
meter in throttle

50% open
The meter in pressure
controls the spool
100
200

10bar

A B
100
P T

250 bar

21 | IHA Dresden
 Lowering valve
100 100
200 200
No vacuum!
velocity control with 0 0
meter in throttle

50% open

the meter in pressure

100
controls the spool 200

10bar

A B

P T 50

250 bar

22 | IHA Dresden
 Lowering valve
100 100
200 200

Velocity control with 0 0

meter in throttle No vacuum!
100% open

The meter in pressure

100
controls the spool 200

10bar

A B
50
P T

250 bar

23 | IHA Dresden
 Without lowering valve
100 100
200 200

Without load-lowering
0 0
valve
?
25% open

100
200

10bar

A B

P T

50
250 bar

24 | IHA Dresden