User guide

Winching Principles
10
X Calculating Fleet Angle
To obtain the best wire/synthetic rope service, the direction of pull will be on a horizontal within
±15 degrees and perpendicular to be centerline of the winch drum within ±5 degrees. If the fleet
angle is bigger than the recommended angles, a good spooling cannot be obtained as the rope will
spoon onto one side of the rope drum and possible damage to the rope or winch.
X
Load Rating
Load and speed varies according to how much
wire/synthetic rope is on the drum. The first layer of rope
on the drum delivers the slowest speed and the maximum
load. A full drum delivers the maximum speed and the
minimum load.
For this reason, all automotive winches are rated at their
first layer capacities.
X
Required Pulling Force
You need a winch powerful enough to overcome the weight of your vehicle with the added
resistance caused by the obstacle, moving water, mud, snow, sand or on a steep hill.
As a general guide, you need a winch with a maximum line pull of at least 1.5 times greater than
the gross vehicle weight.
There are three factors listed that influence the line pull effect required to recover the vehicle. The
values and calculations in this section are approximate and are for reference only.
a). Gross vehicle weight
b). Type of the surface to be traversed
c). Gradient to overcome
In recovery and loading the winch is used to pull something, the required pulling force (RPF) can
be calculated according to the formula:
RPF = (Wt X S) + (Wt X G)
Where: Wt = The gross vehicle weight
S = The type of the surface to be traversed
G = The gradient to overcome
Surface Type Surface Drag (S)
Gradient Angle (θ) Gradient (G)
Metal 0.15
5% 3° 0.06
Sand 0.18
10% 6° 0.11
Gravel 0.20
20% 11° 0.2
Soft Sand 0.22
30% 17° 0.3
Mud 0.32
50% 26° 0.44
Marsh 0.52
70% 35° 0.58
Clay 0.52
100% 45° 0.71
Top layer (Max. speed Min. load)
Half layer (Med. speed Med. load)
First layer (Min. speed Max. load)
Flange of drum