Implements or apparatus for applying pushing or pulling force – Single throw lever – Lazy tongs
Patent
1991-05-07
1993-03-09
Kisliuk, Bruce M.
Implements or apparatus for applying pushing or pulling force
Single throw lever
Lazy tongs
187 18, 182 63, B66F 322
Patent
active
051920530
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The invention relates to a device for initiating a lifting movement in a lifting mechanism, for instance in lifting tables, including a least a first lifting arm and a lifting second arm, articulatedly interconnected by means of a first joint, the lifting mechanism also including a force applying means acting on one of the lifting arms, the force applying means and the lifting arms being oriented generally parallel with respect to each other in the initial position, before the initiation of the lifting movement.
BACKGROUND OF THE INVENTION
Devices of the kind mentioned above are to a great extent used for instance in lifting tables, which in the initial position, before initiation of the lifting movement, should have a very low height, i.e. wherein lifting arms and the force applying means included in the lifting table preferably should be oriented generally parallel to each other on the ground. In order that it may be possible to initiate a lifting movement in this case, it is necessary that the connection of the force applying means to the lifting arms is designed especially with regard to this. Examples thereof are the devices disclosed in the Swedish specifications 8304655-7, 8501852-1 and 8602983-2, the U.S. Pat. Nos. 2,862,689 and 2,937,852 as well as German patent specification 17 56 270. In all these devices the lifting movement is initiated by the means that the end of the power applying means forces apart obliquely oriented glide surfaces arranged on each lifting arm, for instance by means of a roller arranged at the end of the force applying means. The force applying means here generally comprise hydraulic cylinders. These previously known constructions function in an excellent way, but, since the glide surfaces are subjected to comparatively large forces from the force applying means when the lifting movement is initiated, these glide surfaces may be subjected to wear and/or deformation, which may have detrimental effect on their function. The construction with rollers and slide surfaces is comparatively expensive and complicated. In addition to this, comparatively high hydraulic pressures generally are necessary due to the specific geometry which is a result of the resulting, comparatively short, effective length of the arms of leverage, which results in that high demands have to be made on the hydraulic equipment.
U.S. Pat. No. 3,991,857 furthermore discloses a lifting device of the kind mentioned in the introduction, in which a roller indirectly is guided and forced in between two surfaces obliquely oriented relative to each other (one oblique surface being arranged on one of the lifting arms and one being the base plate) by means of a complicated system of control plates and abutments guiding the movements of the roller. This device in principle functions in a similar way as the devices described above and suffers generally from the same disadvantage.
U.S. Pat. No. 2,899,172 finally discloses a lifting device of the kind mentioned in the introduction which is constructed and intended for trucks. In this device the lifting movement is initiated by means of a lever acting against the truck frame. This construction thus is limited to a use in connection with stable frames of the kind used in truck frames.
SHORT DESCRIPTION OF THE INVENTIVE CONCEPT
The present invention intends to provide a device for initiating a lifting movement in a lifting mechanism as described above, which is simple in function, construction and operation and in which the force applying means can be dimensioned for comparatively small forces, i.e. that hydraulic devices, if such are used, only are subjected to comparatively low pressures. This is to be achieved while maintaining an extremely low constructional height in the initial position before the initiation of the lifting movement. This is achieved in that the force from the force applying means is transmitted to the first lifting arm by means of a double-armed lever which is connected to the first lifting arm by means of a sec
REFERENCES:
patent: 2899172 (1959-08-01), Cresci
patent: 3032319 (1962-05-01), Dale
patent: 3330381 (1967-07-01), Halstead
patent: 3991857 (1976-11-01), Wolk et al.
patent: 4526346 (1985-07-01), Galloway et al.
Kisliuk Bruce M.
Morgan Eileen P.
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