Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-12-23
2001-09-25
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Attachment
C280S764100, C280S766100, C212S302000
Reexamination Certificate
active
06293586
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns a mobile working machine having a chassis supporting the working machine, at least four wheels pair-wise associated with wheel axles and connected to a frame by interposed wheel springs pre-tensionable by the effect of the load exerted on the axle, with two support legs provided laterally one opposite the other on the sides of the frame and associated with one of the wheel axles, preferably the back axle, which have a foot apart which can be extended downwardly and supported on the ground with raising of the chassis off the ground, and at least one blocking mechanism able to selectively release or block the spring path of one of the wheel springs.
2. Description of the Related Art
Mobile working machines, such as cement pump trucks, must be set up stably on the ground at the work site. For this, they are provided with support legs in the area of the front and/or rear axles. Conventionally, prior to the supporting process, the rear axle is so blocked or arrested on the frame of the vehicle chassis, that during the subsequent extension of the foot parts, they do not have any spring action or only slight spring action and the wheels are lifted off of the ground. For this a blocking mechanism is provided, which selectively blocks or releases the spring path of the wheel springs. The arresting of the axle in a case of mobile cement pump trucks is necessary, in order to increase the stability of the vehicle during pivoting out of the distribution mast. The raised rear axle serves at this time as ballast and contributes to the improved stability of the stance. Besides this, in the case of cement pump trucks with rear material receiving containers there is a reduction of the fill height, which is an advantage during filling with cement.
The most commonly employed technique for spring blocking in the case of cement pumpers involves chains, which prior to the bracing are hooked into a hook provided fixed to the frame. It has already been proposed to carry out the bracing process with the aide of a manually operated hydraulic cylinder. For avoiding the danger of an accident and damage, the axle arresting means must again be released after termination of the work process.
SUMMARY OF THE INVENTION
Beginning therewith, the invention is concerned with the task of improving the known mobile working machine of the above-described type in such a manner, that with little construction expenditure a reliable operation of axle arresting is made possible.
The inventive solution is based on the idea, that the operation of arresting the axle can be simplified or facilitated, when an automatic axle arresting occurs during the bracing process. In order to achieve this, it is proposed in accordance with the invention that, during extension of the foot part, a blocking device is automatically moved in the blocking direction and, during retraction of the foot part, is automatically moved in the release direction. Therein the blocking mechanism is directly or indirectly controlled via the foot part or the control mechanism which operates the foot part.
A preferred design of the invention envisions, that the blocking mechanism is slideable or pivotable between a release and a blocking position relative to a position fixed on the frame directly or indirectly under the influence of the foot part, and which can be arrested relative to the frame at least in the blocking position. Further, the blocking mechanism preferably includes an at least partially flexible or bendable tension member, which on its one end is anchored or connected to the blocking device and on its other end is connected to either the frame or on a frame supporting part of the wheel spring, wherein in the former case supplementally on a wheel supporting side of the spring a direction-changing linkage is provided fixed on the spring, and in the latter case a frame fixed direction changing linkage for the tension member is provided. When the blocking device is in the blocking position, the tension member limits the spring path of the pre-tensioned wheel spring, while in the released position of the blocking device it gives way to the spring path of the wheel spring.
In order to take up the forces acting on the tension member during the blocking of the axle, it is advantageous, when the tension member is guided by at least one further frame-fixed redirection guide. In order to achieve a controllable positioning of the tension member in the released position, it is proposed in accordance with a further preferred embodiment of the invention, that a flexible segment of the tension member is bridged over by a draw-spring which takes up play. Therein the tension member or segment thereof can be formed at least partially as a flexible draw rope or as a chain.
A further preferred embodiment of the invention envisions that the blocking device is constructed as a pivot lock, pivotable between a releasing position and a blocking position, provided fixed on the frame or on a frame fixed part of the support leg, connected with the tension member and pivotable between the blocking position and releasing position via a controlling device associated with the extendable foot part. The pivot lock therefore is preferably pivotable in the direction of the blocking position against the force of a spring engaging on the tension member. The control device preferably includes a control curve slideable against a knuckle provided on the slide lock eccentric to the pivot axis thereof and a blocking surface which arrests the pivot lock in its blocking position. The blocking surface preferably engages on the control curve, so that the knuckle or cam in the blocking position of the pivot lock runs upon the blocking surface, wherein the blocking surface is directed partially in the extension direction of the support foot. It is advantageous, when the pivot lock is pivoted 90° between the release position and the blocking position about its axis, and thereby takes along the tension member. The inventive control device and the pivot lock ensure therefore, that for blocking and for releasing the wheel axle only a relatively short part of the displacement length or stroke of the foot part is necessary, so that the predominant portion of the support movement occurs while the wheel axle is arrested. The steeper the control curve is in the extension of the foot part, so much the shorter is the path of travel required of the foot part for arresting process. In order to reduce the friction during the position changing process, it is preferred that the cam is a roller cam.
When the wheel spring is constructed as a leaf spring, on which the wheel supports are secured via spring stirrups or U-clamps, it is of advantage, when the spring fixed transmission linkage or the spring fixed anchoring position of the tension member is provided on a plate fixed to the spring clamp. When in contrast the wheel spring is designed as a pneumatic spring with variable air pressure, it is of advantage, when the air pressure in the air spring during extension of the foot part is automatically reduced, preferably to atmospheric pressure, and that during retraction of the foot part the air pressure is increased via a pressurized air supply unit. For this purpose there is advantageously envisioned a reversing process, which is controlled directly or indirectly via the foot part or the blocking mechanism, and thereby acts upon the air spring selectively with air pressure or with atmospheric pressure.
REFERENCES:
patent: 3780891 (1973-12-01), Steiner
patent: 3781035 (1973-12-01), Petersson et al.
patent: 3825280 (1974-07-01), Myers
patent: 3871685 (1975-03-01), Senelet
patent: 4444416 (1984-04-01), Soderstrom
patent: 4466637 (1984-08-01), Nelson
patent: 4583760 (1986-04-01), Halstensgaard et al.
patent: 5387071 (1995-02-01), Pinkston
patent: 5575493 (1996-11-01), Schwartz et al.
patent: 5961145 (1999-10-01), Schillinger et al.
Lum L.
Pendorf & Cutliff
Putzmeister Aktiengesellschaft
Swann J. J.
LandOfFree
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