Fire escape – ladder – or scaffold – Platform with elevating or lowering means
Reexamination Certificate
1999-10-12
2001-04-17
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Platform with elevating or lowering means
C182S146000
Reexamination Certificate
active
06216820
ABSTRACT:
This application claims priority to German application numbers 197 15 176.0, filed Apr. 11, 1997, and 197 17 060.9, filed Apr. 23, 1997 and European Application Number PCT/EP98/02050.
This invention relates to an elevating work platform comprising a working platform which is guided for vertical movement on at least two mutually parallel masts, and which has a carriage for each mast which is guided on the respective mast and has a driving unit, wherein the working platform is supported on the carriage by means of joining elements, and power transmission between the mast and the carriage takes place by positive locking.
Elevating work platforms of this kind are known from prior art. The same are as a rule raised instead of scaffolds in the area of building facades. The working platform of such an elevating work platform encompasses the masts on at least three sides, wherein it is usual that the working platform also laterally protrudes beyond the two masts. The masts consist of mast elements which are arranged course by course one on top of the other and are connected to cach other, so that masts of a desired elevation can be raised from a plurality of mast elements. For power transmission a driving unit is normally used which is arranged on a motor supporting plate and has at least one electric motor with a transmission unit flanged to it. The motor supporting plate is part of the carriage, wherein the transmission unit includes on the output side at least one output pinion meshing with a rack which is fixed to the mast.
With elevating work platforms of this kind the problem exists that, although motor control is correspondingly monitored, the driving power is different on the two masts, which fact may in case cause a slight difference of level of one carriage compared to the other. This difference of level may be the result of uneven loading of the working platform and causes that the working platform is not always fully horizontally aligned. An inclination of the working platform thus produced leads to material stress both in the masts and the working platform together with the connected driving members, by which material stress the structural components are subjected to undesired loads. In addition, it is necessary that the corresponding loads are determined and are used for controlling the elevating work platform. This requires the driving motors to be switched off if inadmissible loads occur in the elevating work platform.
Starting from this prior art the invention is based on the object of further developing an elevating work platform in such a way as to make it possible by simple means to compensate the movement of the working platform relative to the masts, which compensation is necessary due to the load to which the platform is subjected and due to construction tolerances, so that high levels of tension in the elevating platform are avoided.
The solution of this problem provides for the joining elements between each carriage and the working platform being so configured that the working platform is supported both for a limited displacement relative to the carriages in its longitudinal axis direction and for a limited rotation relative to the carriages at right angles to its longitudinal axis direction.
By the configuration according to the invention of this elevating work platform it is guaranteed that the working platform is movable relative to the masts to such an extent that a slightly different running of the driving motors for both carriages can be compensated. Namely, the working platform can be moved relative to the carriages in its longitudinal axis direction as well as relatively rotated about the carriages. Of course, these relative movements are possible only to a very limited extent in order not to have a negative influence on the working safety of such an elevating work platform. But due to the mobility of the working platform relative to the carriages moments in the junction points between the carriages and the working platform are considerably reduced. In addition, tension is reduced also in the masts and particularly in the driving elements, i.e. the racks and the pinions of the driving units meshing with the racks.
According to a further feature of the invention it is provided that the joining elements consist of a rod cylindrical in cross-section and of a spherical member supported in a holding device. The rod tends to enable an axial displacement of the working platform relative to the carriages, whereas the spherical member enables the working platform to rotate relative to the carriage.
Preferably, the rod is connected to the working platform, and the spherical member is movable relative to the rod. Consequently, the rod is configured to be stationary, whereas the spherical member is movable along the rod.
The rod is, according to a further feature, supported in a bore penetrating the spherical member. Consequently, the spherical member can be moved relative to the rod in the longitudinal axis direction thereof and rotated about the rod.
Each carriage preferably has two rods which are supported in corresponding spherical members, one of the rods being arranged in the vicinity of the carriage and the other one on the end of the working platform, which is spaced from the carriage. The carnage preferably has a motor supporting plate with supporting profiles which are arranged at right angles to the working platform and on which the working platform takes support. The motor supporting plate includes an opening which is penetrated at least by the output pinions in order that the same mesh with the rack. The transmission unit is fixed with a housing to the motor supporting plate, preferably by means of screws, and carries on its end opposite to the motor supporting plate the driving motor which together with its shaft carrying the driving pinion protrudes into the transmission unit and is screwed to the transmission housing.
The holding device for the spherical member is configured as a pot-shaped bearing shell which has radially opposing openings that receive the rod. These openings also determine an angle of pivoting of the rods about the longitudinal axis of the bearing shell. In this way a further degree of freedom of the rod relative to the bearing shell and, accordingly, to the carriage is determined.
Preferably, the bearing shell is covered by a lid. The bearing shell can, in the usual manner, be filled with a lubricant such as grease, for example, in order to guarantee movement of the spherical member within the bearing shell free of wear. It is, however, also conceivable for the bearing shell and/or the spherical member and/or the rod to have a wear-reducing surface coating, for example polytetrafluor ethylene, in the region of the spherical member. The lid placed onto the bearing shell prevents the penetration of dirt particles such as mineral grains, dust or the like. It must be taken into account here that elevating work platforms as presently discussed are used in construction sites where a corresponding amount of dirt is to be expected.
According to a further feature of the invention it is provided that the holding device is supported on a profile of the carriage, under the interposition of a force-sensing device. In this way the static load of the working platform can be measured by means of this force-sensing device. If the static load of the working platform reaches an inadmissible high value which is predetermined in a computer, the drive will be blocked through this computer. In this case the starting, i.e. moving of the platform is inhibited until it is signalized by the force-sensing device that this inadmissible high load of the working platform does no longer exist.
The force-sensing device preferably is in the form of a wire strain gauge. Finally, according to a further feature of the invention it is provided that the carnage includes two joining elements with associated force-sensing devices. This enables the loads of the working platform to be measured in the longitudinal direction and in a direction at right angles to the longi
Chin-Shue Alvin
HEK Manufacturing B.V.
Locke Liddell & Sapp LLP
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