Grapple buckets are a type of attachment used on a skid-steer, which is a type of heavy machinery steered by applying the brakes to the wheels of one side of the vehicle. Skid-steer operators use grapple buckets to further secure a load being transported in the bucket; tines are mounted to the top lip of the bucket, and when a load is present in the bucket, the tines can clamp down on the load to secure it. The grappling tines or arms are controlled by hydraulic cylinders for strength and stability.
Skid-steerers, often known as skid loaders, tend to be smaller machines than other types of front loaders. The grapple buckets used on these machines will therefore be smaller as well, though they are still exceptionally useful for pushing materials, loading the materials into trucks, and so on. Grapple buckets are commonly attached to skid loaders when the materials being pushed or lifted do not sit well in the bucket alone. Tree branches, for example, can stick outside of the bucket or fall out easily if not secured properly; the grappling arms or tines can clamp down on the branches, ensuring they do not fall out during transport.
When not clamping down on materials, the grappling arms or tines stick straight up to avoid interfering with the loading of the bucket. Small hydraulic pistons control the position of the tines on grapple buckets. These hydraulic arms consist of stanchions that contain oil or fluid, and pistons that are mounted within the stanchion. As the oil inside the stanchions are pressurized, the pistons will shoot outward, clamping the grappling arms or tines downward onto the materials within the bucket. When the pressure is released, the pistons will retract, allowing the tines or arms to release and rise upward. The hydraulic functions are controlled by the operator, who sits in a cockpit behind the bucket and uses hand levers and other controls to operate the machine.
The grapple buckets and tines or arms are usually made from high-grade, thick steel that will endure regular use and abuse. It is likely the steel will be coated with some sort of protective paint or sealant to prevent premature rusting, wear, or other decay, though this sealant often wears out quickly after regular use. The lower lip of the bucket is usually flat and straight to accommodate front loading, though in some cases, the bucket may feature teeth for grabbing or digging.