Many factors impact machine stability on slopes; boom length, load carried and load overhang have a direct influence on stability. Dynamic load swing and ground conditions also affect stability, while operator experience and training on a specific machine are critical to safe slope operation.

Factors impacting pipelayer stability on slopes

Caterpillar has conducted static and dynamic testing of current and predecessor pipelayer models in regards to lift capacity and performance in slope applications.

Boom length

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Boom length is the single most important controllable factor in determining slope capability. Static and dynamic testing has indicated that for each 1.2 m increase in boom length, slope capability is reduced by approximately 3 degrees.

Safety Tip 1

When working in slopes choose the shortest length boom available to accomplish the task.

Load

Increased load has a direct correlation to diminished slope capability.

Safety Tip 2

Always know your load. In multiple machine lifts, understand the limits and capability of each machine. Carry your load as low as possible to the ground.

Load overhang

Carrying your load at longer overhangs has a positive impact on fore-aft slope capability. Carrying your load at a 4.3 m overhang improves slope capability by approximately 1 degree over carrying the load at a 1.8 m overhang.

Safety Tip 3

Always carry your load as far out as possible without impacting your side tipping point.

Load swing

Every degree of load swing impacts the machine stability comparable to a degree of slope. Shifting loads can cause the machine to become unstable.

Safety Tip 4

Make every effort to control the load. In multiple machine lifts, the lifts should be co-ordinated.

Ground conditions

One classic misconception regarding the operation of pipelayers on slopes is that the machine will perform according to the known ground angle. Ground conditions can significantly impact the slope capability of a pipelayer. Changes in machine orientation relative to the measured slope can have a detrimental impact to slope performance.

Safety Tip 5

Holes, soft areas, rocks, uneven matting, water bars and other obstacles can change the effective machine angle relative to the slope. This change in effective machine angle can be significant. Care should be taken to remove obstacles when operating on slopes.

Operator experience

The skill of each operator is very important in determining the successful operation of pipelayers on slopes. Before sending an operator to a jobsite where slopes are present, ensure that the operator has a thorough understanding of machine controls, and the safety features incorporated into the machine. The operator should be trained on the machine that is being operated, and should have a comprehensive understanding of actions to be taken in a dangerous situation.

Safety Tip 6

The operation and maintenance manual (OMM) should always be available to the operator. The operator must read and understand the information contained in the OMM.