Implements or apparatus for applying pushing or pulling force – Portable implements or apparatus for tensioning flexible... – Including rotatably driven drum for engaging either material...
Patent
1983-10-03
1985-09-24
Levy, Stuart S.
Implements or apparatus for applying pushing or pulling force
Portable implements or apparatus for tensioning flexible...
Including rotatably driven drum for engaging either material...
254223, 254369, 24 68CD, 1401235, B21F 900, B25B 2500, B66D 114
Patent
active
045428832
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a tensioner for straps and especially to such tensioners for use in systems for keeping loads in position, with an anchoring means for the fixed end of the strap and with a tightening ratchet for working a strap drum, that is designed for acting as a winch and has a locking pawl that may be moved clear of it.
It has been seen from experience that when the straps of load securing systems are done up with such a tensioner they are frequently overly loose or overly tight so that in the first case there is a chance of the load slipping out of position, whereas in the second case there is a chance of the load being damaged or of the straps being torn.
SUMMARY OF THE INVENTION
For this reason one purpose of the present invention is that of designing a strap tensioner of the sort noted hereinbefore, in which the torque taking effect on the strap drum on tensioning the same is limited to a maximum value so that the tightening operation may in each case be undertaken till this torque is produced. This purpose is effected in keeping with the present invention inasfar as the tightening ratchet has tooth means on the side of the strap drum so that a driving pawl, that is fixed to the ratchet lever and is more especially pre-loaded by a spring towards the axis of the strap drum by spring means, may be put in driving connection with the said tooth means, and the ratchet lever has means limiting the torque transmitted to the tooth means on working the ratchet lever. Such a design of the strap tensioner in keeping with the invention is sturdy and simple in structure, that may nevertheless be used quite safely even under rough working conditions.
In keeping with a first form of the strap tensioner, the driving pawl is able to be moved, is placed tangentially in relation to the strap drum and is springingly pre-loaded in the tensioning direction tangentially in relation to the strap drum so that on going past a torque level, as produced by the ratchet lever on the strap drum, the driving pawl gives way, it then slipping over the tooth means on the strap drum without driving same any further. Herein the wording "tensioning direction" is used in the sense of that direction, in which the strap drum is turned and the strap is tensioned when the ratchet lever is moved in this direction. It is best if the pre-loading effect on at least one spring, with which the driving pawl is pre-loaded tangentially towards the strap drum, is adjustable. An especially useful effect is to be accomplished if the turning of the ratchet lever and of the strap drum are the same, this provides better conditions for control over the full tensioning range.
As part of a further form of the invention, that is especially of value, the ratchet lever has a division along its length direction into two parts that are joined together by a mechanism causing a bending of the ratchet lever when there is a torque greater that a certain torque at the free end of the ratchet lever. In this respect the user will then clearly be able to see that he has got to the maximum torque by such folding or giving away and he will not undertake any further fruitless attempts at further tightening the strap by using the strap tensioner.
The part of the ratchet lever nearer to the strap drum is best made with at least the same length as the part thereof further from the said strap drum, and especially is up to 20% longer than it.
A useful effect has been produced by making the ratchet lever of two arms with a spacing therebetween at least equal to the width of the strap, said arms being joined together at their free ends by a handle and being joined together at the point of division by the mechanism for limiting the torque.
Within the framework of a preferred form of the invention, this mechanism has a pin joined rigidly with the outer part of the ratchet lever and having at one point a polygonal cross section onto which a sleeve is seated so that it may be moved in the length direction. The sleeve is pre-loaded in o
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Hail III Joseph J.
Levy Stuart S.
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