Choosing the Right Strop and Shackle for Towing

LOAD RESTRAINT & RECOVERY

HOW TO DETERMINE THE RIGHT STROP AND SHACKLE FOR TOWING AND RECOVERY

NEVER USE A TOWBALL!
After-market front mounted bullbars must have chassis mounted recovery points.

NEVER USE VEHICLE SHIPPING LUGS OR LASHING POINTS!
Many underground mine vehicles and light trucks have hooks or very tight pin/clevis recovery points. Black Snake Recovery Strops have thimbles and round eyes designed to suit couplers, shackles or hooks of greater minimum break strength (MBS) than the recovery strop. In an overload situation the loadbearing fibres and rubber cover will separate from the steel eye and steel connectors. The thick rubber cover dampens recoil of loadbearing fibres in a safe failure mode leaving all steelwork safely attached to vehicles. Maintain your recovery points in good condition and ensure they are strong enough. Black Snake engineered round eyes spread the load on pins to avoid high pressure point loading. Weld stronger recovery points on large vehicles by increasing pin/clevis size, use higher grade steel or consult with your equipment supplier for well engineered solutions.

Remember that all steel work must be stronger than the recovery strop.

The cast clevis and pin arrangements on mining trucks must provide adequate strength and security when used with Body Up Safety Strops. These are safety devices. It is critical to calculate the maximum possible loads or seek OEM advice instead of assuming that all the equipment is properly matched. In the case of Body Up Safety Strops, failure of any component can lead to injury or death if the mining truck’s dump body falls or is accidentally powered down to the chassis.

Skid mounted plant and specialized equipment will generally have pin/clevis or inbuilt heavy lugs (pad eyes) with plate thickness and holes designed for shackles of a certain size. Ensure that shackles are correctly matched to the recovery strop. Safety bow shackles (with bolt and nut) are preferable to screw pin shackles. Ensure that personnel are correctly trained to attach these shackles to equipment and strops. Lugs and pad eyes on the front of mining and road trucks must be linked to the vehicle chassis.

Steel plate thickness and hole size should not allow undersize shackles to be mounted or installed. Bolster or cheek plates on lugs can be used to discourage the use of under-size shackles. Signage on recovery points can also be very useful.

Bulldozers are excellent recovery vehicles on soft, muddy or wet terrain. Bulldozers
have high drawbar pull and good available traction.

A D11T can have a drawbar pull up to 100t-130t at 1-2kph and weights of 105t-115t. Rolling resistance of tracked vehicles can be up to 10% of vehicle weight on soft, muddy roads, which should be considered if a bulldozer is recovering a bulldozer.

A constant steady pull is required in the early stages of recovery using a bulldozer. The bulldozer ripper shank is strongest near the ripper beam assembly.

The photo shows a ripper modified with a mounting bracket for the Bulldozer
‘B’ fitting.

If a winch assembly is mounted, pin/clevis tow assemblies are often available.