Rough Terrain Cranes
Rough terrain cranes have been in existence for the past 30 years. They are also known as "RT" cranes or "off-road" cranes. An RT crane typically has a hydraulic boom, four tires, two axles, and features four-wheel drive and all-wheel steering, increasing maneuverability for off-road operations. Common uses for an RT crane include off-road job sites where there are tight clearances, such as petrochemical plants, refinery maintenance or refinery shut downs. Capacities of an RT crane range from 30 to 130 tons. RT cranes have boom lengths that range between 80 and 140 feet. Recently customers have learned the advantage of the highly mobile RT crane and have demanded higher capacities from the crane. The demand for RT 780, RT 1000 and the new RT 1120 has skyrocketed. Larger RT cranes have replaced the small crawler crane as the off-road crane of choice.
Crawler cranes, also referred to as lattice boom crawler cranes, are the largest of the cranes. Due to the size of the lattice crawler cranes, they have to be transported and assembled on site and are usually in operation for long durations. With tank like features, the crawler's capacity ranges from 40 to 2,000 tons and can reach heights up to 700 feet, with a radius of 500 feet. Most manufacturers offer multi-functional jib systems that increase lift reach and maneuverability. With the low transport height on the crawler's undercarriage, the cranes can be operated on the poorest terrains, making them ideal for turn key projects.
Hydraulic Truck Cranes
Hydraulic truck cranes, or HTC, are very popular for short term or in and out jobs. HTC's are street legal and can be operated with one or two-man crews, making them easily transportable. With street accessibility and a lightweight two axle and eight wheel suspension, HTC's can function at almost any job site. Hydraulic trucks range from 30 to 600 ton capacity and feature a hydraulic boom that can reach lengths up to 200 feet.
Tower cranes are stationary and are the tallest standing of the cranes. Towers are primarily used for high rise building construction and are in operation for long durations. These cranes are transported to job sites and then must be assembled using a mobile crane. The biggest benefit of a tower crane is that it can be operational in tightly confined areas and offers a large picking radius. Often the cranes are connected to an adjoining building to support extreme reach heights of over 600 feet. Tower cranes come in many styles, such as hammerhead, flat-top, self-erecting or luffing jib configurations and have a 100 to 800 ton meter rating.
All Terrain Cranes
All Terrain cranes are mobile cranes that have the ability to travel at high speeds on public roads. On rough terrain job sites, they utilize all-wheel and crab steering to maneuver through tight spaces. All Terrains have anywhere from 2-9 axles and can lift loads up to 1,200 tons.
Auxiliary Hoist - A supplemental hoisting unit, usually designed to handle lighter loads at a higher speed than the main hoist.
Boom - The large arm mainly responsible for lifting.
Cab - Operator's compartment on a crane.
Capacity - The maximum rated load (in tons) which a crane is designed to handle.
Chain Hand - The chain grasped by the operator to apply force required for lifting, lowering, or traveling motions.
Chain Load - The load-bearing chain in a hoist.
Counterweights - Multi-ton weights placed on the back of the cab to prevent the crane from tipping during lifts.
Jib - Lattice structure that extends out of the boom.
Load Moment Indicator - Array of lights located in the cab just above the operator's eye level; flashes if crane's lifting limits are reached.
Outriggers - Supports that keep the crane balanced.
Rotex gear - Large Gear under the cab that allows the boom to be rotated.
Sheave - A pulley with a grooved rim for retaining a wire rope that is used for hoisting or hauling.
Two-gear pump - Hydraulic pump system that uses two rotating gears to pressurize oil.