Got this info
here (page 6). Condensed
My 4x4 usually weighs close to 3000kg (6600lb) on a trip. To move or pull a vehicle on a firm flat bitumen surface requires a force of about 10% of the loaded weight of the vehicle. Gravel or grass increases this to about 33%. The limit of a towballs capcity WITHOUT a snatch strap.
1lb equals 0.454kgs, or 1kg equals 2.2lbs.
Bogged
Bogged to the Base of the Wheel Rim, needs a pull of about 100% of the load.
Bogged to the wheel Hub, requires a pull of 200% of the load.
Bogged to the Belly or the Chassis, 300%.
Slope
• 15degree Slope = add +25% of the weight
• 30degree Slope = add +50%
• 45degree Slope = add +75%
For a Decline, or Downhill, change the "plus" to a "minus".
Example
I'm bogged to the Hubs on a 30 degree slope. (3000+50%)x2=9000kg (19800lb). Way beyond a towballs capacity
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