COMEUP Utility Duty Winch (Ver:00) - Manual (Page 6)

I I . Winching Principles
4
Calculating Fleet Angle
To obtain the best wire 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.
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 utility duty winches are rated at
their first layer capacities.
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)
Metal 0.15
Sand 0.18
Gravel 0.20
Soft Sand 0.22
Mud 0.32
Marsh 0.52
Clay 0.52
Gradient Angle ( ) Gradient (G)
5% 3° 0.06
10% 6° 0.11
20% 11° 0.2
30% 17° 0.3
50% 26° 0.44
70% 35° 0.58
100% 45° 0.71
°