The present invention relates to a device for measuring and checking occasionally the tension forces prevailing at any location along a chain.

When loads are lifted with the aid of chains, it is some¬ times necessary to be able to measure and check quickly the tension forces which prevail in the chain or chains by means of which the load is lifted, to thereby prevent overloading in one of the chain sections or to establish that the load is suspended correctly in relation to its centre of gravity, or to the weight the load directly when a single- part chain is used.

One object of the invention is to provide a portable measuring device which can be quickly connected to and detached from the chain at any location therealong, with¬ out requiring the chain to be detached from either the lifting hook or the load, and without requiring the use of tools for connecting the device to or detaching the device from the chain.

Tn accordance with the invention, this object is achieved in that the measuring device comprises a main body which is effective in taking up load and which has located at each end thereof a chain-link engaging member and which takes-up the tensile load on the chain between said mem¬ bers, and which measuring device also includes means for measuring and indicating the tension force or strain taken-up by the main body. Thus, the link-engaging members can be readily hooked sequentially onto a chain subsequent to relieving the load on said chain, so that the chain part located between the engaging members has no load

acting thereon and so that the forces acting oh the chain when the load is lifted are instead taken-up by the main body of the measuring device. In this case, the measure¬ ment indicator will indicate the actual tensile load concerned. When the tensile load has ceased, the device can be detached, by simply unhooking it from the chain.

Each engagement member will suitably have the form of a bifurcate claw having a pocket into which a chain link can be inserted, the pockets facing towards one another so as to facilitate attachment and detachment of the device to and from the chain.

The pockets are preferably configured so that the force lines of the chain parts coacting with respective claws extend in line with the longitudinal symmetry axis of the device, thereby preventing undesirable deformation or distortion of the main body of said device.

The invention will now be described in more detail with reference to the accompanying drawings, in which

Figure 1 is a side view of the inventive device attached to a chain shown in dash dotted lines; and

Figure 2 is a side view of the device seen in the direc¬ tion of the arrow A in Figure 1.

The inventive device intended for measuring and checking tension forces at any desired location along a chain in¬ cludes an elongated main body part 10 which has a bifur¬ cate claw 12 provided at each end thereof. Each claw 12 has two legs 12a, 12b which define centrally therebetween a groove or slot 14 (Figure 2) which is intended to re- ceive a chain link 16a of a chain 16. The claw legs 12a, 12b also define a pocket 18 into which a link 16b con-

nected to the link 16a can be inserted. The pockets 18 have a depth such that when a link 16 is inserted fully into the pocket, the force lines of the chain parts coupled to respective claws 12 will extend in line with the longitudinal symmetry axis B of the main body 10.

The main body 10 has mounted thereon a measuring in¬ strument 20, which is illustrated schematically in Figure 1. The measuring instrument may include, for example, a strain gauge or some other suitable means for detecting the tensile force or strain acting in the main body 10 and therewith in the chain 16, and an indicating means which is connected directly thereto and which indicates the tensile force acting in the chain.

The invention device can be connected to a chain quickly and easily, so as to permit the tension forces acting therein to be checked. The device is attached to the chain by hooking respective claws onto the chain (prior to sub- jecting the chain to load), so that the tension forces to which the chain is subsequently subjected will be taken-up by the main body 10 through the claws 12. Subsequent to measuring the tensile forces, the device can be unhooked quickly and easily from the chain, after relieving the chain from the load acting thereon.