Preference is to be given to diagonal lashing rather than top over lashing, as no special static tension forces have to be applied. Unlike top over lashing, only low tension forces are applied to the lashing equipment/lashing points. The lashing equipment is only loaded with higher tension if the forces occur due to heavy braking, starting up or by driving around a tight curve.

Attention must also be paid to several special features with diagonal lashings:

These involve the arrangement and location of the lashing rods relative to the respective loading directions. It is comparable with the angle geometry of slings in which an angle of 60° may not be exceeded. Otherwise the load in the anchoring legs would increase disproportionately.

However, in diagonal lashing 2 angle planes (horizontal and vertical) must be taken into account and therefore two angles must be defined. Angles α and β are decisive in the calculation. Angle β is the horizontal angle between an imaginary straight line from the lashing point in the direction of the driver's cab and the chain leg.

The vertical angle α is the angle between the payload area and the chain leg.
If β is very small, a very high load occurs in the lashing equipment on driving around curves.

If β is very large, a very high load occurs on braking/accelerating.

In the extreme case with angle α = 90°, an infinitely high force would theoretically occur in the lashing equipment. In particular, this explanation is intended to illustrate that extreme cross-wise lashing as restraint in the direction of travel, as often found on construction vehicles or rollers, is the most unfavourable type of load restraint in the direction of travel.

At an angle α the optimum lashing equipment force yield exists between 0° and 30°. As α increases, the load in the lashing equipment increases too and at an angle of 90° is theoretically infinite.

Calculation example of the allowable tensile force (loading capacity LC) according to the following formula:

Excavator

m = 18000 kg ≈ 18000 daN = G
Vertical angle of the lashing legs: β = 10°
Horizontal angle of the lashing legs: α = 40°
Number of effective lashings in the respective direction: n = 2
Coefficient of friction µ if wooden payload area is dirty/icy: µ = 0

cos 40° = 0-766
cos 10° = 0.984

LC = 9552.31daN
For the excavator with a weight of 18000 kg and the lashing arrangement shown, lashing equipment must be selected which at least has the allowable lashing capacity of 9552.31 daN.
This would, for example, e our 20-t heavy-duty ratchet or an ICE VSK 10, size 10mm.