Rigging Angle Calculator How To Reduce The#

However, if you are given other values of angles that may be greater than 90 or even 180, you might want to check out our reference angle calculator to help you determine the angle you need.The angle at which a sling is used, and the number of legs lifting the load can significantly effect its capacity. Doing so will provide you with the angle from the horizontal. If an angle from the vertical is given, just subtract this angle from 90.

It will want to spool towards the centre and so leave gaps. If the fleet angle is too big, the wire will tend to pull away from the flange as the layer changes. With all types of drum, the rope is subject to a fleet angle which directly influences its behaviour and impacts on its service life. 6.92 tonnes is the maximum weight that can be lifted.You may know the importance of fleet angles, but do you know the best ways to correct them? Cris Seidenather, managing director of Lebus International Engineers, explains how.When spooling wire rope onto a drum, it is necessary for the rope to come onto the drum at a very slight angle, just enough to encourage each wrap to sit tidily next to the previous wrap, and for each layer to ride cleanly onto the layer beneath.In fact, apart from the design of the drum itself, this angle – the fleet angle – is the most significant factor in the behaviour of a spooling system.Put simply, optimum fleet angle means maximum rope life and smooth, safe spooling operations.The fleet angle is defined as the largest angle of the rope between the first sheave and the drum flange, relative to the centre line of the drum. Therefore: Max load 8 x 1.73 x 0.5 6.92 tonnes. The safe working load limit (mechanical advantage) is the maximum load in pounds which should ever be applied, and when the load is applied uniformly and in direct tension to a straight segment of wire rope.This means a factor of 1.73 for the angle and another factor of 0.5 for the reeve.

Nor has it been calculated mathematically. This is not an absolute rule of physics it depends on the rope construction. Again, catastrophic failure and personal injury is a real threat.Ideally, the fleet angle should be between 0.25 and 1.25 degrees. It will pile up on the flange for, perhaps, two or three wraps and then bang down with considerable force, damaging the rope and the equipment.

Rigging Angle Calculator How To Reduce The

The rope must go from the drum over the compensator sheave with a minimum contact angle of 60 degrees to a fixed point such as a fairlead or fixed sheave. As the rope winds or unwinds, the FAC shaft slowly oscillates, allowing its sheave to slide back and forth across the shaft to maintain an optimum fleet angle and guide the rope smoothly onto the drum.Certain operating conditions are necessary for the Lebus fleet angle compensator to function properly. Both offer a solution to guide the cable along the drum between flanges, but each has its advantages and disadvantages.The fleet angle compensator (FAC) is driven by the movement of the wire rope as it goes through the crossover sections of the drum. The other is a level winder that is mechanically driven. One is a fleet angle compensator, which is driven automatically by the rope tension. There is often no space to rig a sheave the requisite distance from the drum, and so an alternative for how to reduce the fleet angle must implemented.For just such cases two additional spooling devices are available.

But mechanical level winders also work perfectly well and have much less to go wrong. And third, it is completely automatic and, after initial adjustments when the rope is first spooled onto the drum, only a minimum of maintenance is necessary.Level winders can be quite sophisticated pieces of kit, hydraulically or electrically driven and computer controlled. Second, installation is easy and quick.

It is adjusted for the specific rope diameter, and the gear ratio is fixed (using a standard sprocket-chain connection) to match the ratio between coils of wire on the drum to the pitches on the lead screw. In this case, the system can be set up anywhere around the drum.The level winder is engineered to be compatible with the parallel grooving on the drum. Perfect, controlled spooling is guaranteed regardless the number of layers and slight changes in wire rope size.The level winder unit – also sometimes called level wind pay-on gear – must be installed in front of the drum in line with the first fixed sheave when using the vertical rollers to guide the wire rope.Alternatively, a sheave can be integrated and installed within the housing frame. The automatic level winder fitted is designed and engineered to be compatible with the grooving on the drum. The lateral movement of the housing is generated by a chain drive sprocket ratio between drum and lead screw, as shown in the image. The rope feeder housing includes two vertical roller bars and one horizontal roller or, alternatively, a wire rope sheave.

A flat iron plate, which we call a kicker plate, is welded or bolted onto a specific point on the flange of the winch drum. In case of damage to a mechanical level winder, parts are easy to replace and there is nothing electrical or hydraulic to worry about.Oceanographic installations that spool rope up to 46 layers have demonstrated that level winders give synchronised and totally controlled spooling in the very harshest, most testing conditions.The disadvantages of level winders is that they do require a little more space than fleet angle compensators and they are sensitive to high axial forces and shock loads.If the fleet angle is just a bit too small, there is a really rather simple solution. As with the fleet angle compensator, once it is set up no more adjustment is necessary and very little maintenance is required. There must be a minimum tension of 1 to 2% of the wire rope’s breaking load when spooling more than one layer.The advantages of level winders are that they keep the rope spooling properly even if there is slack in the line. To avoid excessive angles of the rope on the sheaves, the minimum distance to the fairlead or fixed sheave must be at least seven times the drum width. The rope must go from the drum through the vertical rollers or the level-wind sheave to a fixed point such as a fairlead or fixed sheave.

The parallel grooving of the drum will continue to act effectively to provide smooth multi-layer spooling with a narrower drum, even if – as is likely – the number of layers on the drum needs to increase as a consequence of narrowing the width. Once installed near the centre line of the groove crossover sections, the rope is given a kick after each complete wrap to take its proper position on the patterned drum.A final option for adjusting the fleet angle, if it is not possible to move the fixed sheave, is simply to reduce the width between the flanges. Since the Lebus parallel grooving pattern on the drum controls the movement and spacing of the wire rope between the flanges, and from layer to layer, it is easy to identify the location on the drum circumference where the rope must return (kick back) from the flange to regain the proper position to assure proper spooling for each repeated layer.This is where the kicker is placed.