Thursday, March 10, 2011

How to Use a Snatch Block - Winching Basics

If you are into trucks, ATVs, or just general off-roading, you will surely encounter winches and winching. Winches are mechanical devices used for pulling loads by winding up a high-tension cable into a spool. In off-road vehicles, winches are normally located on top of the front bumper, attached to the main frame of the vehicle for a solid anchor.

If you already know the basics of winches and winching, the next logical "upgrade" would be to use a winch snatch block. A snatch block is basically a pulley that attaches to a solid anchor point. It provides a sort of "detour" for the cable, in cases where it needs to go into a different direction (angle), or back to itself (later I will explain why this is essential).

If you have no idea what a winch snatch block looks like, try searching for some photos so you can understand this article better.

The most basic configuration of the block is the one where the pulley is sandwiched between two side plates. By the way, the pulley is the round wheel where the rope will tread. The side plates attach to the pulley via an axle or a pin-in all, the pulley is free to rotate while sandwiched between the plates. The plates are also normally rectangular in shape and the pulley is at the far end of the two. The opposite ends of the plates have holes. These holes are where you can attach chains and or a tree strap.

If you are familiar with the laws of physics and where pulleys fall into those laws, you would know that pulleys can be used to amplify pulling force. For example, if you have 100 pounds worth of pulling force on a rope, you can get as much as 200 pounds worth of pulling power by simply using a pulley in between the rope and the object. The amount of amplified force a pulley adds depends on the angle of the bend of the rope. Obviously, a rope that runs through a pulley-all in a straight line-is useless.

To use a winch snatch block, run the main cable of the winch through the pulley. If you have found a solid anchor point, run a strong strap or chain around it and insert it through the holes of the block's side plates. Make sure the block is really, really secured to the anchor point. If you have a tree as an anchor point, use a flat strap instead of a chain as chains can hurt trees.

Going back to using a snatch block to go back to the source wherein the cable makes a u-turn or a complete 180-degree turn, this setup is normally used to winch your vehicle out of stuck situations. Obviously, if the tires are unable to grip and move the vehicle, you need to have something pull you out. If no other vehicle is available, a simple snatch block can do the trick.

By the way, snatch blocks are called as such because it literally "snatches" some of the force that normally is fully handled by the winch. Snatch blocks can also relieve winches of some stress and heat buildup.

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