ANCHORING
Anchoring is a technique used to increase the friction between your truck and the surface of the ground. The most common way of increasing your anchorability is to apply ALL of its brakes. The same calculations for determining the resistance of a casualty apply to the winching source. By increasing the anchorability that your truck creates you’re able to anchor more weight.
Anchor Ability: The primary way to anchor a road vehicle is to apply all of its brakes.
Weight of tow truck multiplied by “Damage Resistance” 0.666 or 2/3 = total anchorability (when all of the brakes are applied)
WAYS TO ANCHOR
OUTRIGGERS
Outriggers, also commonly referred to as stands or spades, are extendable legs that can be used to increase a wrecker’s anchor ability. They can be laid level on a surface to give the truck additional points of contact with the ground, or can also use teeth to dig into pavement, gravel or dirt to provide a stronger grip.
When using the outriggers, be sure that the teeth will not hit anything buried such as pipes or electrical wiring. You also want to be careful not to damage the surface they come in contact with.
WOODEN WEDGE OR WHEEL CHOCK
Two pieces of hardwood can be used to create a wedge can increase the anchor ability of a wrecker. You will likely need to prepare for this by cutting the hardwood to size. If you are only using one, install it on the inner of the dual wheels in case a second needs to be installed. The same result can be achieved by using a manufactured tire chock. Be sure to place the hardwood wedge or tire chock on both rear tires.
SCOTCH BLOCK
A scotch block is a wedge used to increase the anchor ability of a wrecker. After hooking the winch line to the casualty, the wedge is placed behind the rear tire with a chain hooked into a key-hole slot at the rear of the wrecker. After putting in neutral, as the winch gathers line, the recovery vehicle will roll back onto the scotch block pushing the teeth into the ground/surface stopping when the chain gets tight that is attached to the keyhole slot.
WEDGING DUAL TIRES
By placing a 4 by 6 inch piece of hardwood between the rear dual tires of a wrecker or truck, the vehicle’s anchor ability can be increased. The wood should be placed at the based on the front tire angled towards the top of the rear tire, causing the tires to lock. Be sure to remove the wood prior to driving.
If the wrecker does not have dual tires, the same affect can be achieved by placing the piece of hardwood between the rear tire and the spade or outrigger, as demonstrated in the image above.
WEDGING DUAL TIRES
This technique can also be used on the casualty. If the brakes are not working on a casualty that is being winched on a gradient, blocking the tires with hardwood will prevent the casualty from rolling once the winch line has been removed. This allows a wrecker to winch a casualty over a bank, as demonstrated in the image to the right.
THE ‘DO-NOT’S’ OF ANCHORING
USING THE WHEEL LIFT
The wheel lift of your wrecker should not be used as a way to increase anchor ability. This can cause damage to the wheel lift and the wrecker body itself. However, there are manufacturers that have created spade / outrigger attachments for wheel lifts. These should not be used unless the operator has a thorough understanding of the capabilities and limitations of the spade attachments.
TYING DOWN THE FRONT
The front of the wrecker should not be tied down to increase anchor ability under any circumstance. These tie downs put too much stress on the frame which can cause damage or lead to a catastrophic failure.