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Parallel strokes with hydraulic cylinders

Parallel strokes with hydraulic cylinders

  • Rams travel parallel to each other when extending and retracting regardless to axial loading

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  • The rams keeps the load still while staying parallel

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  • Rams can be used to press, pull och lift

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  • A simple system without external components

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  • Single or double acting system

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  • Two, three, or four rams can operate parallel to each other

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  • Reliable and economic

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  • Download Product Data Sheet

 

 

 

 

The figure shows a KC 125/75 x 150 series coupled with a KC 100/60 x 150. The tractive area of the larger ram is identical to the piston area on the smaller. To compensate any micro-leakage past seals and evacuate air, a self-adjusting valve has been incorporated into each ram.

Parallel strokes with hydraulic rams

This illustration shows four series coupled rams with a built-in self-adjusting valve. The valve is required to compensate any skewing of the load caused by micro-leakage past seals. A skew position will occur if the rams aren't fully extended/retracted during normal operation. To correct this, fully extend/retract the rams. The built-in self-adjusting valve will then automatically remove any skew position.

System pressure will not increase more than load requirement (disregarding pressure drop) even though the self-adjusting valves are open when the rams are fully extended/retracted.

The precision of the parallel motion is due to the fact that an equal quantity of oil is always kept between rams. Any skew position that may occur can be caused by elasticity in the hydraulic lines (use piping when possible) and to a certain extent, oil compression.

Parallel strokes with hydraulic rams

 

Technical data

Tie rod hydraulic cylinder, measurements 1

Tie rod hydraulic cylinder, measurements 2

  KC
25/16
KC
32/20
KC
40/24
KC
40/30 (24)
KC
50/30
KC
60/33
KC
60/40 (33)
KC
70/36
KC
80/39
KC
80/60 (39)
 KC
100/60
KC
100/75 (60)
KC
125/75

KC
160/100

KC
200/120		 KC
250/150
Max pressure in bar

300

 260 290 290 200 200 200 230 200 200 200 200 210 250 290 300
(Max pressure on request)   300 300 300 260 280 280 280 240 240     240   290  
                                 

Push force in tonnes at 200 bar

 1
1.6
 2,5
2.5
3.9
 5.7
5.7
7.7
 10.1
10.1
 15.7
15.7
24.5
40.2
 6238 98,2
Pull force in tonnes at 200 bar 0.6
1.0
 1,6
1.1 (1.6)
2.5
 3.9
3.1 (3.9)
5.7
 7.7
4.4 (7.7)
10.1
6.9 (10.1)
15.7
24.5
 40,2 62,8
Plus area (cm²) 4.9
8.0
 12.6
12.6
19.6
 28.3
28.3
38.5
 50.3
50.3
 78.5
78.5
122.7
201.1
 314.2 490.9
Minus area (cm²) 2.9
4.9
 8.0
5.5 (8)
12.6
 19.6
15.7 (19.6)
28.3
 38.3
22 (38,5)
50.3
34.3 (50.3)
78.5
122.5
 201.1 314.2
Cylinder diameter (inner) 25
32
 40
40
50
 60
60
70
 80
80
 100
100
125
160
 200 250
Piston rod diameter 16
20
 24
30
(24)
30
 33.2
40 (33.2)
36
 38,7
60 (38.7)
60
75 (60)
75
100
 120 150
A ± 2mm 96
95
 114
105
123
 131
131
131
 131
144 (131)
182
178
178
190
   266
B (2) 10
10
 10
10
10
 10
10
10
 10
20 (10)
20
20
20
20
 20 30
C 28
32.6
 41
41
48
 58
58
66
 74
74
 90
90
114
150
 190 244
D M6
M6
 M8
M8
M8
 M10
M10
M12
 M12
M12
 M16
M16
M20
M30
 M36 M45x2
E (3) M10
M10
 M12
M12
M12
 M16
M16
M20
 M20
M20
 M24
M24
M24
M42
 M80x3 M100x3
F G 1/4"
G
1/4"
G 1/4"
G
1/4"
G
3/8"
G 3/8"
G
3/8"
G
1/2"
G 1/2"
G
1/2"
G
1/2"
G
1/2"
G
1/2"
G
3/4"
G
1 1/4"		 G
1 1/4"
G 39
45
 55
55
62
 80
80
88
 100
100
 120
120
150
200
 250 320
H (2) >15
>15
 >20
>20
>20
 >25
>25
>25
 >25
>25
 >30
>30
>40
>50
 >50 >75
I ± 2mm (1)  
146,5
 176,5
167,5
190
 207
207
263
 263
286 (263)
374
374
374
492
    
J  
18
 27,5
27.5
31
 35
35
61
 61
61
88
88
88
141
    
K  
15
 20
20
25
 30
30
35
 35
35
 50
50
50
80
 100 120
L  
45
 50
50
60
 70
70
83
 83
83
 123
123
123
180
   350
M (flange width)  
18
 20
20
25
 30
30
21
 21
21
 30
30
30
47
   75
N (tolerance f8)  
34
 42
0 (42)
52
 62
62
70
 80
80
 92
0 (92)
105
150
 163 200
O  
10
 10
0 (10)
10
 10
10
10
 10
10
 15
0 (15)
15
15
 20 20
P  
32,5
 35
35
40
 45
45
71
 71
81 (71)
108
108
108
161
    
Q (ball width)  
12
 16
16
20
 22
22
25
 25
25
 35
35
35
55
   85
R (flange width)  
18
 20
20
25
 30
30
30
 30
30
 40
40
40
60
   75
S  
26,5
  
25,5
37
  
42
33
  
44 (34)
 60
60
60
54,3
 77 74.5
T (1)  
58
  
69
74
  
77
82,5
  
85,3 (82)
 101
101
101
115,8
 317.5 325.5

The colors show the cylinders that fit together in so-called parallel strokes, when the pressure and tensile area must be equal between the different cylinders.

Dimensions in brackets refers to altenativ piston rod diameter.
Measure N and O are introduced gradually from 2001-06-30, always notify if you will attach the cylinder at the front.

(1) Measurement + stroke length
(2) Other measurements on request
(3) Piston rod is custom machined to all possible designs
We reserve the right to design changes. Updated 2011-11-11

 

 

Our hydraulic rams for parallel strokes in operation at Kalmar Industries

Kalmar Industries is a global provider of container and heavy duty materials handling equipment. 2004 they took three new 25 tonnes hydraulic lifts in operation, to manage the truck frame in an ergonomic and efficient way for assembly.

To the right you can see the lift as a CAD model, completely designed and manufactured by LALMEK. The stability of the lateral is the pass between the pit walls in the floor and the metal sheets which the cylinders are attached to. Piston is Ø75 and Ø60, and despite the lifting height of 1100 mm the lift is stable.

Our hydraulic rams for parallel strokes in operation at Kalmar Industries

 


The lift is located in a recessed metal sheet box in the floor. In that way you get a completely flat floor when the lift is not used. Production Technician Ove Johansson of Kalmar, together with Per Lagerlöf Amab made the mechanical arrangement and all adaptations to different variations of "Light Trucks". LALMEK has designed and manufactured the hydraulic parts. LALMEK also made some laser cutting and welding, and made the lift ready for immersion in the pit.

An interesting bit to solve was that during the assembly of the counterweights, the front part of the truck would become so light that the truck would overturn backwards. What further complicated the whole thing was that Kalmar wanted the lift to be lowered down by its own weight in order to avoid the assembly carriages would be exposed to hydraulic gun. The truck frame is therefore attached to the lift, and by placing the largest and the smallest cylinder next to each other in the back of the truck, the front with the third cylinder can't move without the back is being lifted or lowered at the same time.

The concept of three series connected KC-cylinders can easily be changed to deal with other truck models and other tempos in truck manufacturing.


Carriage for enamelled truck frame docked to the lift to ensure right positioning before lifting. When the lift is not used, the floor is flat.
(Unfortunately, there was no unassembled frame at shooting moment)

Ove Johansson is very pleased with how easy the assembly is by changing the height. Thanks to the slim design and central location the
lift is never in the way of assembly.


Here we see all three lifts. The first is raised to show how it looks.
It is normally in the same level as the floor when not in use.


Here you can see the front wheel axle assembled, and then lowered down for easier access from the top.

 


(c) 2000-2012 LALMEK Verkstad AB