Traversing hoists – Adjustable to transport or nonuse position – Collapsible or foldable boom
Reexamination Certificate
1999-11-18
2001-07-17
Brahan, Thomas J. (Department: 3652)
Traversing hoists
Adjustable to transport or nonuse position
Collapsible or foldable boom
Reexamination Certificate
active
06260720
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a two arms system, and more specifically, toward an improved two arms system for a unit crane.
BACKGROUND OF THE INVENTION
There is a considerable call for a two-armed system for unit cranes, for instance. Such a crane consists of a rigid arm and thereafter an arm composed of a number of part-arms joined together which can be influenced hydraulically in such a manner that the part-arms form a polygon. This arm is in turn attached to a stand or to said stand via a supporting arm. The two arms in the system, together with a supporting arm if used, can thus be arranged to be situated one above the other and also so that all the arms are extended. Various units can be attached at the tip of the rigid arm, for use in clearing trees and bushes. Units functioning as excavators or loading means can also be attached, or even a concrete pump or concrete hose. In existing systems with two arms, the arm able to form a polygon is influenced by a hydraulic unit arranged between the arm parts so that, when the polygon is extended, the unit is located substantially in the middle of the polygon. Certain problems have been found to occur when operating such two-armed systems, as regards speed control of the top of the rigid arm, and problems also occur as regards the force exerted at said tip. Such a unit crane is suitable fitted on a caterpillar vehicle and this involves the problem of how to fold up the crane when it is not in operation. The arms will usually have a substantially vertical position, or they will be situated on the roof of the vehicle. There is also the problem of the actual joints of the unit arms being as stable as possible.
SUMMARY OF THE INVENTION
The object of the present invention is to solve the above-mentioned drawbacks and this is achieved by it being possible for both the arms in the system to be caused to lie one above the other, and possible also above a supporting arm so that, when the arm system is not in use the free end of the arm with several parts is attached either to a stand or to one end of a supporting arm, the other end of which is journalled in the stand. When folded up, therefore, the actual working tip or crane tip of the journalled package will be situated at the opposite part of the stand. To achieve suitable lifting power and suitable speed the crane tip is moved from a packaged position to the position is assumes when the tip is furthest away from the stand. The hydraulic mechanism influencing the arm with the many parts is arranged so that it influences two points situated outside two adjacent arm parts.
According to a preferred embodiment of the invention it is suitable to use a supporting arm which is in connection with a stand. In this case it is advisable to use two pairs of hydraulic cylinders. One pair of hydraulic cylinders is connected to the stand and to a point between the ends of the supporting arm. The supporting arm can be caused to move about its journalling point by means of one of the hydraulic cylinders. At the point between the two ends of the supporting arm it is suitable to arrange a bearing for a pair of hydraulic cylinders, one end of which is connected to said journalling point and the other end of which communicates with one end of the arm that can form a polygon. The first pair of hydraulic cylinders is used so that one hydraulic cylinder of the pair controls the movement of the supporting arm while the other hydraulic cylinder, together with the second pair of hydraulic cylinders, forms a closed hydraulic system, and since the second hydraulic cylinder in the first pair is parallel with the hydraulic cylinder infulencing the movement of the supporting arm, the second hydraulic cylinder in the first pair will automatically control the movement of the two hydraulic cylinders influencing the arm able to form a polygon. This arrangement of hydraulic cylinders provides smoother movements of the whole crane, as well as enabling savings in energy.
The stand to which the supporting arm is attached can be caused to moved in a number of different ways known per se. However, it has proved particularly advantageous if the stand is provided at its journalling end with one or more toothed wheel rims situated one above the other, each cooperating with a chain designed for cooperation with a toothed wheel, each chain being joined at its ends and the chains being influenced by a hydraulic system so that the chains are caused to move and influence the pin of the stand in order to effect movement of the stand.
The arrangement described above with toothed wheel and chain allows the crane to be moved as large an angle as possible in both direction. However, if the demand for a large turning angle is not so great, it is much simpler and less expensive to use two links joined together for each piston rod.
Such a unit crane with its stand is suitable arranged on a platform provided with cab in such a way that the arm system in the form of a package does not come into contact with the cab in any way. The vehicle carrying the crane package may be part of a centrally controlled vehicle in which the engine is jointed to the supporting part for the crane package. By arranging the hydraulic unit outside the arm with the many part arms, the advantage is gained that the crane can be brought to be more or less horizontal with the various arms arranged one after the other and that it can be caused to assume a substantially downwardly-directed vertical position and upwardly-directed vertical position. The many joints in the arm system are subjected to considerable strain and it is therefore suitable for two arms to be combined so that one arm has two parallel shafts between which a pin located on the other arm is passed. The pin and the two arms together form a through-hole for a shaft journal. Each end of the shaft journal is provided with a tensioning ring having a conical surface and a tensioning cone, also having a conical surface, cooperating therewith. These two units with conical surfaces are brought into rigid contact with each other since the end cone is provided with a tightening bolt that can be screw into each end of the shaft journal. Reliable functioning of the shaft journal located at a point about which the two arms can be oscillated is thus achieved.
Additional characteristics of the present invention are revealed in the appended claims.
REFERENCES:
patent: 3828939 (1974-08-01), Tranchero
patent: 4770271 (1988-09-01), Tranchero
patent: 5197615 (1993-03-01), Gunnarson
patent: 5507107 (1996-04-01), Pinomake
Gunnarsson Wiking
Lindqvist Karl Gustav
Brahan Thomas J.
Dennison, Scheiner Schultz & Wakeman
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