Information
-
Patent Grant
-
6672430
-
Patent Number
6,672,430
-
Date Filed
Monday, July 9, 200123 years ago
-
Date Issued
Tuesday, January 6, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Kramer; Dean J.
- Chin; Paul T.
Agents
- Davidson, Davidson & Kappel, LLC
-
CPC
-
US Classifications
Field of Search
US
- 187 269
- 187 211
- 254 9 C
- 254 10 C
- 254 122
- 254 124
- 182 63
- 182 141
- 108 147
- 108 136
- 108 144
- 108 145
- 248 421
- 248 588
-
International Classifications
-
Abstract
A method for adjusting a first force applied to a movable element in a first position of the movable element by a force applying device, the force applying device applying a second force to the movable element in a second position of the movable element. The method includes connecting the movable element and a base element with a scissors-type linkage; mounting the force applying device to the scissors-type linkage at a first mounting point; mounting the force applying device to the base element at a second mounting point; and moving at least one of the first and the second mounting points along a constant force curve, so that the second force remains constant as the first force is adjusted. A device for adjusting a first force applied to a movable element in a first position is also provided.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a device and method for adjusting a force applied to a movable element such as a platform.
Scissors-type linkages are used in many devices and machines for providing movable characteristics, e.g. in lifting devices such as liftable platforms. The scissors-type linkage allows for lifting a platform into an upper, open or extended position starting from a lower, close or retracted position in which the platform can come very close to a base or the floor or can even contact one of those.
A movable element such as a liftable platform which is connected, e.g. to a base, a floor, an operation deck or the frame of a machine such as a printing machine, can be moved, e.g. raised, by the operator himself, by a driving device such as a motor or by the assistance of an energy-recycling mechanism or device.
The force which is applied to the movable element has to be adjusted based on the weight of the movable element, the weight of the scissors-type linkage and perhaps on the weight of a load or an operator in the case where the scissors-type linkage is used to lift or hold goods or operators. If no additional loads are present, the force only has to compensate or exceed the gravitational and frictional forces of the mechanism itself.
It is advantageous to use an energy-recycling device such as a gas spring for moving or raising the element. The energy which becomes free when the element is moved in its lower position can then be stored in the energy-recycling device, e.g. in the compression of a gas in the gas spring, and can be used to assist the movement into the upper position.
U.S. Pat. No. 4,712,653, which is incorporated by reference herein, discloses an energy-recycling scissors lift including a platform, a base and a pair of scissors linkages, each having a pair of first and second scissors legs. A bridge structure connects each of the second legs together. A sealed gas cylinder, attached to the base and the bridge structure, moves the platform to an extended position above the base. Energy is stored in the sealed gas cylinder as the platform descends to a retracted position and a compensation device is attached to the scissors lift to compensate for the overforce caused by the sealed gas cylinder.
A weight adjustment mechanism is used which includes means for adjusting the forcing-point radius, i.e the radius of the mounting point of the sealed air cylinder to the bridge structure with regard to the mounting point of the scissors legs at the base, to compensate for and dissipate an amount of overforce imparted by the sealed gas cylinder. Therefore, the weight adjustment mechanism can be used to fine tune a sufficient force that maintains the platform in its extended position, resulting in a scissors lift which can be easily started down to its retracted position. The weight adjustment mechanism can also adjust the upward force needed to start the platform towards its extended position.
The above-referenced patent has the disadvantage that the force applied to the platform in its retracted position can not be adjusted independently from the force applied to the platform in its extended position and vice versa.
FIG. 1
shows a prior art device
1
for lifting a platform
2
. The device
1
comprises a scissors-type linkage
4
, which includes a first scissors leg
6
and a second scissors leg
8
which are connected at a pivot point
10
. A second pair of scissors legs in addition connects the platform
2
and a base
16
but it is not shown for purposes of clarity.
FIG. 1
shows the scissors-type linkage
4
in a closed position or closed mode. The first scissors leg
6
is mounted with one end to the platform
2
at a mounting point
12
whereas the other end is movingly supported by a roll
14
. The second scissors leg
8
is mounted with one end to the base
16
at a mounting point
18
whereas the other end is movingly supported by a roll
20
. The device
1
further comprises a gas spring
22
having a cylinder
24
and a piston rod
26
. The gas spring
22
is mounted with one end to the scissor type linkage
4
at a first mounting point
28
and with the other end at a second mounting point
30
to a mounting plate
32
of the base
16
.
The gas spring
22
applies a force
34
to the platform
2
which assists the lifting of the platform
2
. If an operator grips the platform at a handle
36
and pulls or pushes the platform up, he only has to apply an additional force to the platform so that the sum of the force applied by the gas spring
22
and the force applied by himself exceeds the gravitational force on the platform
2
and lifting device
1
.
FIG. 2
shows the prior art device
1
for lifting the platform
2
, in which the platform
2
is in an upper position and the scissors-type linkage
4
is in an open position or open mode. The gas spring
22
applies a force
134
to the platform
2
which maintains the platform
2
in the upper position, i.e. the force
134
must be equal to or can be greater than the gravitational force on the platform and the lifting device
1
. Advantageously the force
134
exceeds the gravitational force only minimal.
As can be seen from
FIGS. 1 and 2
the second mounting point
30
of the gas spring
22
does not move because it is fixed at the mounting plate
32
of the base
16
. Therefore, the force
134
is smaller than the force
34
as indicated by the respective length of the arrows
34
and
134
. The force applied to the scissors-type linkage
4
and subsequently to the platform
2
by the gas spring
22
depends on the angle between the piston rod
26
and the first scissors leg
6
and it depends on the compression of the gas spring.
Both positions of the platform
2
, the upper shown in FIG.
2
and the lower position shown in
FIG. 1
, can be fixed by the use of a fixing element such as a pin.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and device for adjusting a first force applied to a movable element in a first position so that a second force applied to the movable element remains constant.
It is a further alternate or additional object of the present invention to provide a method and device for independently adjusting a first and a second force applied to a movable element such as a platform.
The terms “first force”, “second force”, “third force” and “fourth force” in this application are used herein solely to distinguish the forces from one another, and are not meant to have any other specific meaning.
The present invention provides a method for adjusting a first force applied to a movable element in a first position of the movable element by a force applying device, the force applying device applying a second force to the movable element in a second position of the movable element, comprising the steps of:
connecting the movable element and a base element with a scissors-type linkage;
mounting the force applying device to the scissors-type linkage at a first mounting point;
mounting the force applying device to the base element at a second mounting point;
moving at least one of the first and the second mounting points along a constant force curve, so that the second force remains constant as the first force is adjusted.
The terms “first mounting point”, “second mounting point”, “third mounting point” and “fourth mounting point” in this application are used herein solely to distinguish the mounting point from one another, and are not meant to have any other specific meaning.
The method according to the invention advantageously allows for compensating for force applying device wear or deviations in strength as it is supplied by the manufacturer, e.g. gas spring wear or deviation. Further, the method according to the invention allows the operators to easily adjust the required force, e.g. a lifting force, to their own liking, preference or need.
According to the invention the method may further comprise the steps of:
providing a further force applying device, the further force applying device applying a third force to the movable element in the first position of the movable element and the further force applying device applying a fourth force to the movable element in the second position of the movable element;
mounting the further force applying device to the scissors-type linkage at a third mounting point;
mounting the further force applying device to the base element at a fourth mounting point; and
adjusting the fourth force applied to a movable element in the second position of the movable element by moving at least one of the third and the fourth mounting points along a constant force curve, so that the third force remains constant as the fourth force is adjusted.
Further the moving of at least one of the first, the second, the third and the fourth mounting point may be along an approximated constant force curve.
In another embodiment of the invention a method for independently adjusting a first and a fourth force applied to a platform comprises the steps of:
connecting the platform and a base element with a scissors-type linkage;
mounting a first gas spring to the scissors-type linkage at a first mounting point and mounting the first gas spring to the base element at a second mounting point;
mounting a second gas spring to the scissors-type linkage at a third mounting point and mounting the second gas spring to the base element at a fourth mounting point;
applying the first force to the platform in an upper position and applying a second force to the platform in a lower position using the first gas spring;
applying a third force to the platform in the upper position and applying the fourth force to the platform in the lower position using the second gas spring;
moving at least one of the first and the second mounting points along a constant force curve, so that the second force remains constant as the first force is adjusted; and
moving at least one of the third and the fourth mounting points along a constant force curve, so that the third force remains constant as the fourth force is adjusted.
The present invention also provides a device for adjusting a first force applied to a movable element, comprising:
a movable element;
a base element;
a scissors-type linkage, the scissors-type linkage connecting the base element and the movable element; and
a force applying device applying the first force to the movable element in a first position of the movable element and applying a second force to the movable element in a second position of the movable element;
the force applying device being mounted to the scissors-type linkage at a first mounting point and being mounted to the base element at a second mounting point, at least one of the first and second mounting points being movable along a constant force curve, so that the second force remains constant as the first force is adjusted.
The device according to the invention can be advantageously used to assist the movement of the movable element, e.g. a liftable platform, which movement can be done by hand by an operator. If the platform is moved into an upper position, the operator can climb up onto it or the platform can be used to lift loads or operators.
According to the invention the movable element may be platform, the first position may be an upper position and the second position may be a lower position.
Further, according to the invention the platform may be a liftable working platform of a printing press and the base element may be part of an operation deck of the printing press.
In another embodiment of the present invention the scissors-type linkage may include at least two pairs of scissors legs, each scissors leg being connect at one end to one of the platform and the base element.
The force applying device may be one of a gas spring, a coil spring, an air cylinder, a pneumatic cylinder or a hydraulic cylinder.
A device according to the invention may further comprise means for moving one of the first and second mounting points along the constant force curve. This means for moving one of the first and second mounting points may include a mounting element movable along a curved slot.
According to the invention the curved slot may approximate the constant second force curve or may be a straight slot.
In a further embodiment of the invention the second mounting point may include a mounting plate pivotally mounted to the base element and having a slot with two ends for receiving a pin, the two ends and the pin limiting the pivotal movement of the mounting plate and the force applying device may be pivotally mounted to the mounting plate.
The present invention further provides a device for adjusting a first force applied to a movable platform of a printing press, comprising:
a base element being part of an operation deck of the printing press;
a scissors-type linkage, the scissors-type linkage connecting the base element and the movable platform, the scissors-type linkage including at least two pairs of scissors legs; and
a gas spring applying the first force to the movable platform in an upper position of the movable platform and applying a second force to the movable platform in a lower position of the movable platform;
the gas spring being mounted to the scissors-type linkage at a first mounting point and being mounted to the base element at a second mounting point, the second mounting point being movable along a constant force curve, so that the second force remains constant as the first force is adjusted.
The device according to the invention may also comprise a further force applying device, the further force applying device applying a third force to the movable element in the first position of the movable element and the further force applying device applying a fourth force to the movable element in the second position of the movable element, the further force applying device being mounted to the scissors-type linkage at a third mounting point and being mounted to the base element at a fourth mounting point. At least one of the third and fourth mounting points may be movable along a constant force curve, so that the third force remains constant as the fourth force is adjusted.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention is described below by reference to the following drawings, in which:
FIG. 1
shows a schematic side view of a prior art device for lifting a platform, in which the platform is in a lower position;
FIG. 2
shows a schematic side view of a prior art device for lifting a platform, in which the platform is in an upper position;
FIG. 3
shows a schematic side view of the device for adjusting a force applied to a platform according to the present invention, in which the mounting point of a gas spring is movable along a constant force curve;
FIG. 4
shows a schematic side view of the device of
FIG. 3
, in which the mounting point of the gas spring is movable along a one of two constant force curves;
FIG. 5
shows a schematic side view of the device of
FIG. 3
, in which the mounting point of the gas spring is movable along an approximated constant force curve;
FIG. 6
shows a schematic side view of the device for independently adjusting two forces applied to a platform according to the present invention, in which the mounting points of a first and a second gas spring are movable along constant force curves;
FIG. 7
shows a detailed schematic side view of a mounting point of the gas spring, in which the mounting point includes a mounting plate;
FIG. 8
shows a detailed schematic side view of a mounting point of the first gas spring, in which the constant force curve is approximated;
FIG. 9
shows a detailed schematic side view of a mounting point of the second gas spring, in which the constant force curve is approximated.
DETAILED DESCRIPTION
FIG. 3
shows a device
101
according to the present invention for adjusting a force applied to the platform
2
in its lower position such as force
34
shown in FIG.
1
. The device
101
comprises a scissors-type linkage
4
such as the one in
FIGS. 1 and 2
which connects the platform
2
and a base
16
which is part of an operation deck of a printing press or a folder. As can be seen from
FIG. 3
the first mounting point
28
of the gas spring
22
is fixed whereas the second mounting point
130
can be moved along a curve
38
. Along the curve
38
several optional positions for the mounting point are shown which does not mean that only a discrete number of mounting points can be realized. It is also possible to move the second mounting point
130
continuously and thereby realize a continuous sequence of mounting points. For example, the second mounting point
130
can be moved along the curve
38
to position
230
so that the gas spring
22
is located in position
122
as indicated by the dashed line gas spring.
The shape of curve
38
can be achieved as follows: The second mounting point
130
is located so that the piston rod
26
is perpendicular to the first scissors leg
6
and that the force
40
applied to the first scissors leg
6
does only have a perpendicular component with respect to the first scissors leg
6
. The compression of the gas spring
22
is preset so that a predetermined resulting force
234
is applied to the platform
2
as indicated by arrow
234
. Then the first mounting point is moved to position
230
which is characterized by the same resulting force applied to the platform as indicate by arrow
234
. The gas spring
22
in position
122
applies a force
42
to the first scissors leg
6
which results in the force
234
applied to the platform
2
. All positions of the first mounting point
130
along the curve
38
, e.g. position
230
, result in the same force
234
applied to the platform
2
. This is because the angle between the piston rod
26
and the first scissor leg
6
and the compression of the gas spring
22
change simultaneously. The curve
38
therefore is a constant force curve, i.e. the force
234
applied to the platform
2
remains constant as the mounting point
130
is moved along the curve
38
. The shape of the curve
38
can be calculated using e.g. a computer and software or can be achieved from experiments.
Whereas the force
234
applied to the platform
2
in its upper position remains constant, the movement of the second mounting point
130
along curve
38
changes the force applied to the platform
2
as if it were in its lower position (similar to that as force
34
). Therefore the constant force curve
38
can be used to adjust the force applied to the platform
2
in its lower position independently from the force
234
applied to the platform
2
in its upper position.
Referring to
FIG. 4
, the second mounting point of the gas spring
22
is moved to and located in a position
330
which is the cross point of a first constant force curve
138
and a second constant force curve
238
. The first constant force curve
138
is achieved like the constant force curve
38
in
FIG. 3
whereas the second constant force curve
238
is achieved vice versa, i.e. starting with the gas spring
22
located perpendicular to the first scissors leg
6
in the closed position of the scissors-type linkage
4
. This position corresponds to the lower position of the platform
2
. The compression of the gas spring
22
is then preset to achieve a predetermined force similar to
34
in FIG.
1
and the second mounting point of the gas spring
22
is moved so that, in dependence of the angle between the piston rod
26
and the first scissors leg
6
in its closed position and the compression of the gas spring
22
the resulting force applied to the platform
2
in its lower position remains constant. The cross point
330
of the two constant force curves
138
and
238
defines the required second mounting point for the gas spring
22
to achieve the predetermined upper force
234
and the predetermined lower force (similar to force
34
) applied to the platform in its upper and lower position.
The force
234
applied to the platform
2
shown in
FIG. 4
in its upper position can be adjusted independently from the force applied to the platform in its lower position by moving the second mounting point of the gas spring
22
along constant force curve
238
and vice versa, i.e. the force
34
applied to the platform
2
in its lower position can be adjusted independently from the force
234
applied to the platform in its upper position by moving the second mounting point of the gas spring
22
along constant force curve
138
.
The second mounting point
130
of the gas spring
22
is mounted to the base
16
or the mounting plate
32
of the base
16
.
FIG. 5
shows the lifting device of
FIG. 3
, in which the mounting point
130
of the gas spring
22
is movable along an approximated constant force curve
338
. As explained above with reference to
FIGS. 3 and 4
the constant force curves can be calculated using e.g. a computer. Adjustments to the force
234
and the lower force (similar to force
34
shown in
FIG. 1
) applied to the platform in its upper or lower position normally are only of small amount and therefore the second mounting point
130
of the gas spring
22
does not necessarily need to be moved all along the constant force curve
38
but perhaps only in a section of the curve
38
. This section can then be approximated by an approximated constant force curve
338
which might be a straight curve or a curve of second order. The calculation of the approximated constant force curve
338
can be done using a computer, and may be a tangent line to the point
130
of curve
38
.
To adjust both forces independently a device
101
as shown in
FIG. 6
can be used. In addition to a first gas spring
122
a second gas spring
222
is mounted to the first scissors leg
6
at mounting point
28
. The force
334
applied to the platform
2
in its upper position is the sum of the resulting first force
336
applied to the platform
2
by the first gas spring
122
and of the resulting third force
338
applied to the platform
2
by the second gas spring
222
. In order to adjust the force
334
, the second mounting point
430
of the first gas spring
122
can be moved along second constant force curve
238
. This movement results in a change of the first force
336
which subsequently results in a change of the force
334
. Both gas springs
122
and
222
also apply a respective force to the platform
2
when the platform
2
is in the lower position which two forces can be summed up to a resulting force. In order to change this resulting force the fourth mounting point
530
of the second gas spring
222
can be moved along the first constant force curve
138
which movement results in change of the forth force applied to the platform
2
in its lower position whereas the third force
338
remains constant.
Therefore, the use of two gas springs
122
and
222
having respective mounting points
430
and
530
which are movable along respective constant force curves
138
and
238
for the upper and lower position of the platform
2
allow for independent adjustment or regulation of the forces applied to the platform
2
in its upper and lower position.
The use of the device
101
as shown in
FIG. 6
to lift a platform
2
allows for independent adjustment or regulation of the forces
34
and
134
as shown in
FIGS. 1 and 2
, so that force
134
may be less, equal or greater than force
34
.
FIG. 7
shows a mounting plate
44
which is mounted to the base or a base element at a pivot point
46
. The mounting plate
44
includes a slot
48
and the base
16
includes a pin
50
which in cooperation limit the possible movement of the mounting plate
44
. The gas spring
22
is pivotally mounted to the mounting plate at cylinder mounting point
52
. A rotation of the mounting plate
44
around pivot point
46
occurs within the limits given by the slot
48
and the pin
50
and moves the cylinder mounting point
52
along constant force curve
38
.
FIG. 8
shows the first gas spring
122
having a mounting point
430
which includes a plate
54
. The plate
54
has a slot
56
which approximates a constant force curve and in which a mounting element
58
is movable. The movement of the mounting element
58
along the approximated constant force curve defined by the slot
56
changes the angle between the gas spring
122
and a scissors leg to which the gas spring
122
is mounted at mounting point
60
and simultaneously changes the compression of the gas spring
122
. Therefore, the resulting force applied the a movable element in a first position remains constant as the resulting force applied to the same movable element in a second position is adjusted.
FIG. 9
shows the second gas spring
222
having a mounting point
530
. A slot
156
in a plate
154
approximates a constant force curve so that the movement of a mounting element
158
within the limits of the slot
156
does not change the force applied to the movable in the second position of the movable element but adjusts the force applied to the movable element in the first position to which the second gas spring
222
is mounted at mounting point
160
.
The two mechanisms shown in
FIGS. 8 and 9
can be used to adjust the forces applied to the same movable element, e.g. the platform
6
shown in
FIG. 6
, in a first and a second position of the movable element independently.
The term “curve” in this application has the meaning of a curve with any shape, e.g. a straight curve.
“Constant force curve” as defined herein includes actual approximated constant force curves, and may include a straight line.
For example by following the exact curve a movement of the mounting point of 10 mm results in a change in a first force of 20.1 lbs whereas the resulting change in a second force is 0 lbs. Further, by following a straight line, which represents the approximated curve, movement of the mounting point of 10 mm results in a change in the first force of 20.8 lbs whereas the resulting change in the second force is 0.9 lbs.
In this case the deviation of the straight line from the exact curve is about 4%, the percentage being defined as X/L, where L is half the length of the straight line and X is the distance of an end point of the straight line from the exact curve.
In general, the acceptable deviation from the ideal curve could be much more than 4%, e.g. when a weaker gas spring is used, preferably less than 25%.
The change in force
2
in the straight line adjustment is only about 5% of the change in force
1
. Therefore, an operator can use the device with the straight line slot to make small changes in force
1
because the corresponding change in force
2
is only 5% and likely not to be noticed in practice. In this case the straight line can successfully substitute the exact curve.
The term “mounting point” in this application does also comprise means for mounting a force applying device to a base element, e.g. a mounting plate, a mounting element, a pin or a slot.
The terms “base” and “base element” in this application do not only mean a separate element to which e.g. a gas spring can be mounted but also mean a machine, a printing press, a folder, the structure or frames of such a machine, printing press or folder, operation decks or platforms.
Claims
- 1. A method for adjusting a first force applied to a movable element in a first position of the movable element by a force applying device, the force applying device applying a second force to the movable element in a second position of the movable element, comprising the steps of:connecting the movable element and a base element with a scissors-type linkage; mounting the force applying device to the scissors-type linkage at a first mounting point; mounting the force applying device to the base element at a second mounting point; and moving at least one of the first and the second mounting points along a constant force curve, so that the second force remains constant as the first force is adjusted.
- 2. The method as recited in claim 1,further comprising the steps of: providing a further force applying device, the further force applying device applying a third force to the movable element in the first position of the movable element and the further force applying device applying a fourth force to the movable element in the second position of the movable element; mounting the further force applying device to the scissors-type linkage at a third mounting point; mounting the further force applying device to the base element at a fourth mounting point; adjusting the fourth force applied to a movable element in the second position of the movable element by moving at least one of the third and the fourth mounting points along a constant force curve, so that the third force remains constant as the fourth force is adjusted.
- 3. The method as recited in claim 2,wherein the moving of at least one of the first, the second, the third and the fourth mounting point is along an approximated constant force curve.
- 4. The method for independently adjusting a first and a fourth force applied to a platform, comprising the steps of:connecting the platform and a base element with a scissors-type linkage; mounting a first gas spring to the scissors-type linkage at a first mounting point and mounting the first gas spring to the base element at a second mounting point; mounting a second gas spring to the scissors-type linkage at a third mounting point and mounting the second gas spring to the base element at a fourth mounting point; applying the first force to the platform in an upper position and applying a second force to the platform in a lower position using the first gas spring; applying a third force to the platform in the upper position and applying the fourth force to the platform in the lower position using the second gas spring; moving at least one of the first and the second mounting points along a constant force curve, so that the second force remains constant as the first force is adjusted; and moving at least one of the third and the fourth mounting points along a constant force curve, so that the third force remains constant as the fourth force is adjusted.
- 5. A device for adjusting a first force applied to a movable element, comprising:a movable element; a base element; a scissors-type linkage, the scissors-type linkage connecting the base element and the movable element; and a force applying device applying a first force to the movable element in a first position of the movable element and applying a second force to the movable element in a second position of the movable element; the force applying device being mounted to the scissors-type linkage at a first mounting point and being mounted to the base element at a second mounting point, at least one of the first and second mounting points being movable along a constant force curve, so that the second force remains constant as the first force is adjusted.
- 6. The device as recited in claim 5,wherein the movable element is a platform, the first position is an upper position and the second position is a lower position.
- 7. The device as recited in claim 6,wherein the platform is a liftable working platform of a printing press and the base element is part of an operation deck of the printing press.
- 8. The device as recited in claim 5,wherein the scissors-type linkage includes at least two pairs of scissors legs, each scissors leg being connect at one end to one of the platform and the base element.
- 9. The device as recited in claim 5,wherein the force applying device is one of a gas spring, a coil spring, an air cylinder, a pneumatic cylinder or a hydraulic cylinder.
- 10. The device as recited in claim 5,further comprising means for moving one of the first and second mounting points along the constant force curve.
- 11. The device as recited in claim 10,wherein the means for moving one of the first and second mounting points include a mounting element movable along a curved slot.
- 12. The device as recited in claim 11,wherein the curved slot corresponds to the constant second force curve.
- 13. The device as recited in claim 12,wherein the curved slot is a straight slot.
- 14. The device as recited in claim 10,wherein the second mounting point including a mounting plate pivotally mounted to the base element and having a slot with two ends for receiving a pin, the two ends and the pin limiting the pivotal movement of the mounting plate; and the force applying device being pivotally mounted to the mounting plate.
- 15. The device as recited in claim 5, further comprising:a further force applying device, the further force applying device applying a third force to the movable element in the first position of the movable element and the further force applying device applying a fourth force to the movable element in the second position of the movable element; the further force applying device being mounted to the scissors-type linkage at a third mounting point and being mounted to the base element at a fourth mounting point, at least one of the third and fourth mounting points being movable along a constant force curve, so that the third force remains constant as the fourth force is adjusted.
- 16. A device for adjusting a first force applied to a movable platform of a printing press, comprising:a base element being part of an operation deck of the printing press; a scissors-type linkage, the scissors-type linkage connecting the base element and the movable platform, the scissors-type Linkage including at least two pairs of scissors legs; and a gas spring applying the first force to the movable platform in an upper position of the movable platform and applying a second force to the movable platform in a lower position of the movable platform; the gas spring being mounted to the scissors-type linkage at a first mounting point and being mounted to the base element at a second mounting point, the second mounting point being movable along a constant force curve, so that the second force remains constant as the first force is adjusted.
- 17. A printing press comprising a device for adjusting a first force applied to a movable element, the device including:a movable element; a base element; a scissors-type linkage, the scissors-type linkage connecting the base element and the movable element; and a force applying device applying a first force to the movable element in a first position of the movable element and applying a second force to the movable element in a second position of the movable element; the force applying device being mounted to the scissors-type linkage at a first mounting point and being mounted to the base element at a second mounting point, at least one of the first and second mounting points being movable alone a constant force curve, so tat the second force remains constant as the first force is adjusted.
- 18. A printing press comprising a device as recited in claim 16.
US Referenced Citations (14)
Foreign Referenced Citations (1)
Number |
Date |
Country |
11060174 |
Mar 1999 |
JP |