Compressible Stop Member For Use On A Crane

• US 20100294736A1
• Filed: 05/17/2010
• Published: 11/25/2010
• Est. Priority Date: 05/20/2009
• Status: Active Grant

• Current Assignee: Manitowoc Cranes LLC (The Manitowoc Company, Inc.)
• Original Assignee: Manitowoc Cranes LLC (The Manitowoc Company, Inc.)
• Inventors: Albinger, Timothy J., Wernecke, Charles R.
• Granted Patent: US 8,910,807 B2
• Time in Patent Office: Days
• US Class Current: 212/293
• CPC Class Codes: B66C 23/92 Snubbers or dashpots for preventing backwards swinging of jibs, e.g. in the event of cable or tackle breakage
• CPC Class Codes: F16F 9/061 Mono-tubular units

Abstract

A compressible stop member for use on a crane includes: a housing having a first sealed end, a second end, a first cylindrical surface and a second cylindrical surface; a free piston slidably contained within the housing in a sealing engagement with the first cylindrical surface; a compressed gas chamber in the housing between the free piston and the first sealed end; and a rod comprising a cylindrical portion with a diameter less than the diameter of the second cylindrical surface and a rod support portion that separates a first liquid chamber comprising the volume inside the housing between the free piston and the rod support portion from a second liquid chamber comprising the volume between the rod support portion and the second end of the housing. Also, the rod support portion includes at least one flow channel allowing liquid to flow between the first and second liquid chambers.

Claims

1. A compressible stop member for use on a crane comprising:

a) a housing having a first sealed end, a second end and an internal surface comprising a first cylindrical surface having a first diameter and a second cylindrical surface having a second diameter;

b) a free piston slidably contained within the housing in a sealing engagement with the first cylindrical surface of the housing;

c) a compressed gas chamber in the housing between the free piston and the first sealed end; and

d) a rod having a first end and a second end, and comprising a cylindrical portion with a diameter less than the second diameter of the housing and a rod support portion, the rod extending out of the second end of the housing with a sliding sealing engagement at the second end of the housing, the second end of the rod being outside said housing;

e) the rod support portion being slidably contained within the housing in a sliding engagement with the internal surface of the housing, the rod support portion separating the volume between the free piston and the second end of the housing not occupied by the rod into first and second liquid chambers, the first liquid chamber comprising the volume inside the housing between the free piston and the rod support portion, and the second liquid chamber comprising the space between the rod support portion and the second end of the housing;

f) wherein the rod support portion includes at least one flow channel allowing liquid to flow unimpeded between the first and second liquid chambers as the rod support portion slides within the housing.

2. The compressible stop member of claim 1 further comprising a rigid stop structure selected from the group consisting of a) the second end of the rod comprising a shoulder that engages the sealed end of the housing, and b) an internal stop located inside the housing past which the rod support portion cannot move.

3. The compressible stop member of claim 1 wherein the sealed end of the housing includes a high pressure relief device.

4. The compressible stop member of claim 1 wherein the sealed end of the housing includes a port that can be opened to introduce gas into the chamber.

5. The compressible stop member of claim 1 wherein the sealed end of the housing includes a port in fluid communication with a pressure gauge.

6. The compressible stop member of claim 1 wherein one of the sealed end of the housing and the second end of the rod comprises a column member engagement surface and the other of the sealed end of the housing and second end of the rod is configured for pivotal attachment to the crane.

7. The compressible stop member of claim 1 wherein the compressible stop member comprises a boom stop, and at least one extension with a hole therethrough is connected to the sealed end of the housing, allowing the housing to be pivotally connected to a crane rotating bed.

8. The compressible stop member of claim 1 wherein the rod support portion comprises a liquid piston and the at least one flow channel through the rod support portion comprises at least two unimpeded flow channels through the liquid piston.

9. The compressible stop member of claim 1 wherein the first and second internal diameters are the same, and the rod support portion is in sliding engagement with the second cylindrical surface.

10. The compressible stop member of claim 1 wherein the amount of liquid in the housing, the configuration of the rod and the configuration of the housing are such that, after the rod is forced into the housing to a first position, the rod and the free piston may make direct physical contact with one another such that further movement of the rod a distance past the first position into the housing will directly force the free piston to move the same distance.

11. A lift crane comprising:

a) a carbody;

b) ground engaging members elevating the carbody off the ground;

c) a rotating bed rotatably connected to the carbody;

d) a boom pivotally mounted on the rotating bed; and

e) at least one compressible stop member, the compressible stop member comprising;

i) a housing having a first sealed end, a second end and an internal surface comprising a first cylindrical surface having a first diameter and a second cylindrical surface having a second diameter;

ii) a free piston slidably contained within the housing in a sealing engagement with the first cylindrical surface of the housing;

iii) a compressed gas chamber in the housing between the free piston and the first sealed end; and

iv) a rod having a first end and a second end, and comprising a cylindrical portion with a diameter less than the second diameter of the housing and a rod support portion, the rod extending out of the second end of the housing with a sliding sealing engagement at the second end of the housing, the second end of the rod being outside said housing;

v) the rod support portion being slidably contained within the housing in a sliding engagement with the internal surface of the housing, the rod support portion separating the volume between the free piston and the second end of the housing not occupied by the rod into first and second liquid chambers, the first liquid chamber comprising the volume inside the housing between the free piston and the rod support portion, and the second liquid chamber comprising the space between the rod support portion and the second end of the housing;

vi) wherein the rod support portion includes at least one flow channel allowing liquid to flow between the first and second liquid chambers as the rod support portion slides within the housing.

12. The lift crane of claim 11 wherein the ground engaging members comprise at least two moveable ground engaging members.

13. The lift crane of claim 11 further comprising at least one hoist drum mounted in a frame secured to the rotating bed, wherein the compressible stop member comprises a boom stop and is pivotally attached to the hoist drum frame.

14. The lift crane of claim 13 further comprising a bumper mounted on the hoist drum frame, wherein the boom stop rests on the bumper when not engaged with the boom.

15. The lift crane of claim 11 further comprising a luffing jib, and the at least one compressible stop member comprises a jib stop.

16. A method of stopping a column member that is pivotally mounted on a lift crane from tipping over backward comprising:

a) providing at least one compressible stop member comprising;

i) a housing having a first sealed end, a second end and an internal surface comprising a first cylindrical surface having a first diameter and a second cylindrical surface having a second diameter;

ii) a free piston slidably contained within the housing in a sealing engagement with the first cylindrical surface of the housing;

iii) a compressed gas chamber in the housing between the free piston and the first sealed end; and

iv) a rod having a first end and a second end, and comprising a cylindrical portion with a diameter less than the second diameter of the housing and a rod support portion, the rod extending out of the second end of the housing with a sliding sealing engagement at the second end of the housing, the second end of the rod being outside said housing;

v) the rod support portion being slidably contained within the housing in a sliding engagement with the internal surface of the housing, the rod support portion separating the volume between the free piston and the second end of the housing not occupied by the rod into first and second liquid chambers, the first liquid chamber comprising the volume inside the housing between the free piston and the rod support portion, and the second liquid chamber comprising the space between the rod support portion and the second end of the housing;

vi) wherein the rod support portion includes at least one flow channel allowing liquid to flow between the first and second liquid chambers as the rod support portion slides within the housing; and

b) attaching the at least one compressible stop member to the crane with a pivotal connection and positioned so that the compressible stop member will engage the column member when the column member reaches a first angle;

c) wherein movement of the column member from said first angle to a second steeper angle causes the rod to be pushed into the housing, thereby forcing the rod support portion toward the free piston, with liquid flowing from the first liquid chamber into the second liquid chamber as the rod travels, creating an increased volume in the second liquid chamber but a decreased volume in the first liquid chamber and a commensurate increase in pressure in the gas chamber and on the rod support portion, thereby impeding the movement of the column member towards the second steeper angle.

17. The method of claim 16 wherein the compressible stop member further comprises a rigid stop structure selected from the group consisting of a) the second end of the rod comprising a shoulder that engages the sealed end of the housing, and b) an internal stop located inside the housing past which the rod support portion cannot move, and when the column member reaches a third angle greater than the second angle, the rigid stop structure is able to prevent any further increase in the column member angle.

18. The method of claim 16 wherein when the column member moves between the first and second angle, the column member first forces the rod into the housing causing an increase of force on the rod proportional to the diameter of the cylindrical portion of the rod, until the rod is adjacent to the free piston;

and then further movement of the column member causes the rod to push both the liquid and free pistons toward the sealed end of the housing, causing an increase of force on the rod proportional to the first internal diameter of the housing.

19. The method of claim 16 wherein the column member comprises said boom and the first angle is between about 75°

and about 80°

, and the third angle is between about 88° and

about 90°

.

20. The method of claim 17 wherein the third angle is the same as the second angle, the a rigid stop structure comprises the rod shoulder engaging the sealed end of the housing, and wherein the rod shoulder comes into contact with the housing at the same rod position as when the rod is adjacent to the free piston.