4:1 Mechanical Advantage Compound Tackle system.

[outback]

Basic tackle systems:

simple tackle.jpg compound pull.jpg

4:1 Mechanical Advantage Compound Tackle system, some points:

1. The Second Line:
This must be a rope, not a strap. This rope must move freely through the snatch block, (SB #1) in the diagram.
Attach a suitably rated shackle to the recovery point on the front of the vehicle. Use a knot such as a bowline or similar to tie the second line to the shackle.
(I carry a 10mm SK75 Dyneema rope, spare winch cable, rated at 12000 lb braking strain for this. It also acts a spare winch cable if necessary.)
This second line needs to be longer than at least half your winch line. Longer the better.

2. Snatch block setup:
Where possible start with the snatch blocks as close as possible, ie near the anchor point.
This allows for a reasonable pull distance before having to reset the system.

3. Loads:
The load at the anchor point is equal to the load you are pulling. The fact you use a 4:1 MA system says these loads are big.
The load on the recovery point where the second line is attached is half the full load.
Where the winch line is attached to the vehicle the load is a quarter of the full load.
The vehicle chassis is imbalance load wise. A big pull may distort things.

4. Winch dampers:
Don’t forget to use these….
(min 3 for this)


Two pictures:
1: initial set up
4-2-1-MA _a.jpg

2: partway into a pull
4-2-1-MA _b.jpg