Tools – Wrench – screwdriver – or driver therefor – Machine
Patent
1996-06-28
1998-10-20
Meislin, D. S.
Tools
Wrench, screwdriver, or driver therefor
Machine
92187, 92256, B25B 1346
Patent
active
058230750
DESCRIPTION:
BRIEF SUMMARY
This is a 371 of PCT/BE94/00072, filed Oct. 25, 1994.
The present invention relates to a hydraulically powered tightening and loosening spanner.
Described in U.S. Pat. No. 4,201,099 is a hydraulic tightening spanner which has a casing/cylinder unit made as a single piece. This embodiment leads to high production costs, given that the casing is difficult to machine. The ratchet wheel of this invention has toothing with a wide pitch, which creates problems during use when the elastic deformation of the rotating parts of the assembly makes them effect a return motion, or alternatively when the supporting element which is to withstand the reaction loading undergoes such bending that the cylinder of the spanner has to effect too great an off-load travel.
The hydraulic tightening spanners described in DE-A-36 20 753 A1 and DE-A-34 16 881 A1 each exhibit an external casing which serves both as a housing and as something for the hydraulic cylinder to react against. The consequence of this is that the external dimensions of the casing are necessarily large or that the hydraulic service pressures have to be increased substantially. This extremely high service pressure means that protection against cracking has to be provided.
In DE-A-36 20 753 A1, the ratchet wheel exhibits very fine toothing as does the drive element. This type of toothing avoids the drawbacks described hereinabove of the toothing of the spanner of U.S. Pat. No. 4,201,099, but by contrast it has the danger of the small teeth breaking which is inevitably incurred because of the nick effect experienced by such toothing.
Hydraulic tightening spanners are also known which have ratchet wheels in which the notches have rounded flanks and rounded drive elements in the form of cylindrical rods or of a pawl with a rounded end (see EP-A-0276936, EP-A-0179543 and U.S. Pat. No. 4,663,997).
The object of the invention is to eliminate all the disadvantages described hereinabove and to obtain a hydraulically powered tightening spanner which simultaneously resists wear and runs no risk of premature breakage. It is also desirable for the spanner according to the invention to have a relatively low weight and small dimensions, and to allow effective and reliable use while still having a long life even when used to full capacity. It is also necessary for all the elements of the spanner to be guided reliably without any possibility of jamming.
To solve these problems, there has been provided, according to the invention, a spanner as described at the beginning, in which the drive lever fixedly supports a guide and the rotational drive member comprises a slide which supports the drive element or elements and is able to slide along the guide during the reciprocating motion of the piston. This embodiment allows the drive element or elements to accompany the rotational motion of the ratchet wheel better. It allows extremely effective interaction between the drive element or elements of a rounded shape and the rounded flanks of the rounded wheel during the outward stroke of the piston rod. Advantageously, the spanner according to the invention further comprises a compression spring arranged between the drive lever and the slide so as to keep the slide and its drive element or elements pressed between the guide and the ratchet wheel assembly.
According to an improved embodiment of the invention, the drive lever and the slide have mutual engagement means which additionally guide the slide in its motion of sliding relative to the guide. These mutual engagement means in particular limit the axial motion of the slide and prevent it from making any motion other than a sliding motion relative to the guide.
To improve still further the interaction between the ratchet wheel and the drive element or elements throughout the entire duration of the outward stroke of the piston rod, the slide may support a cradle which is mounted in the slide so that it can swing about an axis parallel to the axis of the ratchet wheel assembly and in which the drive element or elements is or are housed. A
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patent: 4480510 (1984-11-01), Aparacio, Jr. et al.
patent: 4663997 (1987-05-01), Junkers
patent: 4805496 (1989-02-01), Wagner et al.
patent: 4854197 (1989-08-01), Walton
patent: 5103696 (1992-04-01), Beuke
patent: 5279211 (1994-01-01), Bentz et al.
patent: 5305684 (1994-04-01), Melchior
patent: 5435234 (1995-07-01), Bentz et al.
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