Containerlift
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A Straddle Carrier is a road going truck or semi-trailer used to hoist, stack and transport ISO standard containers. The containerlift loads and unloads the container utilising a pair of hydraulic powered cranes mounted at each end of the vehicle chassis.
The Straddle Carrier was invented during the 1960s in Germany and was further developed by HammarMaskin in Sweden, Steelbro in New Zealand and others. The containerlift has since become an indispensable piece of equipment in many road haulage operations worldwide. The common alternative to the costly machinery of the container lift is to use swap body containers, which are too light to be stacked like "normal" containers, but can be unloaded from a truck by means of foldable legs.
A straddle-carrier may be generally described as having the following attributes:
- Lifting cranes. The hydraulically powered cranes lift the container (from the ground, loading dock, another vehicle, train wagon or other location) on and off the chassis.
- A power source. While typically the cranes are powered by a trailer mounted internal-combustion diesel engine, the cranes are sometimes powered via a PTO from the truck tractor.
- Stabilizing legs. Some Straddle Carriers are fitted with hydraulic legs which permit the operation on unlevel ground and facilitate greater safety margins and load limits when stacking containers.
- Chains, which are attached from the cranes to the base of the container(s) during lifting operations. Some chains are designed to lock two 20’ (1 TEU) containers together allowing the containerlift to lift them as if they were a 40’ container.
- The tractor/cab, which pulls the trailer, and in some cases supplies power to the PTO.
- The chassis, which bears the weight of the container when loaded, as well as supports the cranes.
- The control wand, a device with control buttons typically attached via a lead and which allows the operator to walk around the container and view the unit from various angles during operation.
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[edit] Control and capability
Straddle Carrier machines are designed to lift up to a maximum of 40 tonnes though smaller machines exist.
In addition to controlling the raising and lowering of the cranes, the operator can sometimes tilt the chassis to a limited degree using the stabilising legs which provides a limited ability to operate on non-level ground.
Some Straddle Carriers have a telescopic chassis allowing the unit to expand and contract in order to accommodate 20', 40' or even 45' containers.
[edit] Straddle Carrier safety
Straddle Carrier is rated for loads at a specified maximum weight and length. This information is located on a nameplate provided by the manufacturer, and loads must not exceed these specifications. Straddle Carrier units have been known to overturn, especially when lifting heavy weights, operated on uneven ground and/or when stacking the containers too high.