What is the standard for placing sleepers under crane outriggers?
2 Answers
The standard size for sleepers placed under crane outriggers is 200mmx300mmx800mm, installed vertically. Below is an extended introduction: Purpose: The wooden blocks under truck crane outriggers are used to prevent damage to road surfaces or roofs while ensuring stability against tipping. Normally based on experience, critical situations require mechanical calculations. Material selection: Standard outrigger pads for truck cranes should use hardwood blocks (preferably railroad ties). Principle: Sleepers reduce ground pressure from outriggers. Even concrete surfaces may conceal voids underneath that could cause overturning. A simple example: when lifting 5 tons, the ground pressure differs significantly between a 10.5m boom at 60° and a 20m boom at 40° - lower angles create greater ground pressure. Therefore, using sleepers is essential.
I've worked with cranes for many years. When it comes to placing timber under the outriggers, the standard depends on the actual situation, but generally, the thickness should be around 200mm. If the ground is softer, like mud, it should be increased to 250mm to prevent instability and accidents. The area is also important—each piece of timber should be at least half a meter in length and width to distribute the crane's weight and prevent sinking. The material must be hardwood or steel plates; you can't just use any random wood, or it might crack. I've personally seen a coworker cut corners by using timber that was too thin, and the crane nearly tipped over—it was terrifying. Also, after setting the outriggers, you must shake them slightly to confirm stability—it's basic operational protocol. Otherwise, who takes responsibility if an accident happens? So don’t underestimate this—safety comes first.
