Knowledge Base referenced from Wikipedia
also known as (aka) aerial work platform (AWP), aerial device, elevating work platform (EWP), cherry picker, bucket truck or mobile elevating work platform (MEWP)
A crane is a type of machine, generally equipped with a hoist rope, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy things and transporting them to other places. The device uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly employed in transportation for the loading and unloading of freight, in construction for the movement of materials, and in manufacturing for the assembling of heavy equipment.
There are many different types of cranes, each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings. Mini-cranes are also used for constructing high buildings, to facilitate constructions by reaching tight spaces. Large floating cranes are generally used to build oil rigs and salvage sunken ships.
Some lifting machines do not strictly fit the above definition of a crane, but are generally known as cranes, such as stacker cranes and loader cranes.
Mechanical Principles of Cranes
There are three major considerations in the design of cranes. First, the crane must be able to lift the weight of the load; second, the crane must not topple; third, the crane must not rupture.
Stability of Cranes
For stability, the sum of all moments about the base of the crane must be close to zero so that the crane does not overturn. In practice, the magnitude of load that is permitted to be lifted (called the “rated load” in the US) is some value less than the load that will cause the crane to tip, thus providing a safety margin.
Under United States standards for mobile cranes, the stability-limited rated load for a crawler crane is 75% of the tipping load. The stability-limited rated load for a mobile crane supported on outriggers is 85% of the tipping load. These requirements, along with additional safety-related aspects of crane design, are established by the American Society of Mechanical Engineers in the volume ASME B30.5-2018 Mobile and Locomotive Cranes.
Standards for cranes mounted on ships or offshore platforms are somewhat stricter because of the dynamic load on the crane due to vessel motion. Additionally, the stability of the vessel or platform must be considered.
For stationary pedestal or kingpost mounted cranes, the moment produced by the boom, jib, and load is resisted by the pedestal base or kingpost. Stress within the base must be less than the yield stress of the material or the crane will fail.
Did You Know?
Diesel Force can do 10 year major inspection and certification (10 year test)
Types of Cranes
There are four principal types of mobile cranes: truck mounted, rough-terrain, crawler, and floating.
The most basic truck-mounted crane configuration is a “boom truck” or “lorry loader”, which features a rear-mounted rotating telescopic-boom crane mounted on a commercial truck chassis.
Larger, heavier duty, purpose-built “truck-mounted” cranes are constructed in two parts: the carrier, often called the lower, and the lifting component, which includes the boom, called the upper. These are mated together through a turntable, allowing the upper to swing from side to side. These modern hydraulic truck cranes are usually single-engine machines, with the same engine powering the undercarriage and the crane. The upper is usually powered via hydraulics run through the turntable from the pump mounted on the lower. In older model designs of hydraulic truck cranes, there were two engines. One in the lower pulled the crane down the road and ran a hydraulic pump for the outriggers and jacks. The one in the upper ran the upper through a hydraulic pump of its own. Many older operators favour the two-engine system due to leaking seals in the turntable of aging newer design cranes. Hiab invented the world’s first hydraulic truck mounted crane in 1947. The name, Hiab, comes from the commonly used abbreviation of Hydrauliska Industri AB, a company founded in Hudiksvall, Sweden 1944 by Eric Sundin, a ski manufacturer who saw a way to utilize a truck’s engine to power loader cranes through the use of hydraulics.
Generally, these cranes are able to travel on highways, eliminating the need for special equipment to transport the crane unless weight or other size constrictions are in place such as local laws. If this is the case, most larger cranes are equipped with either special trailers to help spread the load over more axles or are able to disassemble to meet requirements. An example is counterweights. Often a crane will be followed by another truck hauling the counterweights that are removed for travel. In addition some cranes are able to remove the entire upper. However, this is usually only an issue in a large crane and mostly done with a conventional crane such as a Link-Belt HC-238. When working on the job site, outriggers are extended horizontally from the chassis then vertically to level and stabilize the crane while stationary and hoisting. Many truck cranes have slow-travelling capability (a few miles per hour) while suspending a load. Great care must be taken not to swing the load sideways from the direction of travel, as most anti-tipping stability then lies in the stiffness of the chassis suspension. Most cranes of this type also have moving counterweights for stabilization beyond that provided by the outriggers. Loads suspended directly aft are the most stable, since most of the weight of the crane acts as a counterweight. Factory-calculated charts (or electronic safeguards) are used by crane operators to determine the maximum safe loads for stationary (outriggered) work as well as (on-rubber) loads and travelling speeds.
Truck cranes range in lifting capacity from about 14.5 short tons (12.9 long tons; 13.2 t) to about 2,240 short tons (2,000 long tons; 2,032 t). Although most only rotate about 180 degrees, the more expensive truck mounted cranes can turn a full 360 degrees.
Rough Terrain Crane
A rough terrain crane has a boom mounted on an undercarriage atop four rubber tires that is designed for off-road pick-and-carry operations. Outriggers are used to level and stabilize the crane for hoisting.
These telescopic cranes are single-engine machines, with the same engine powering the undercarriage and the crane, similar to a crawler crane. The engine is usually mounted in the undercarriage rather than in the upper, as with crawler crane. Most have 4 wheel drive and 4 wheel steering for traversing tighter and slicker terrain than a standard truck crane, with less site prep.
A crawler crane has its boom mounted on an undercarriage fitted with a set of crawler tracks that provide both stability and mobility. Crawler cranes range in lifting capacity from about 40 to 4,000 long tons (44.8 to 4,480.0 short tons; 40.6 to 4,064.2 t).
The main advantage of a crawler crane is its ready mobility and use, since the crane is able to operate on sites with minimal improvement and stable on its tracks without outriggers. Wide tracks spread the weight out over a great area and are far better than wheels at traversing soft ground without sinking in. A crawler crane is also capable of traveling with a load. Its main disadvantage is its weight, making it difficult and expensive to transport. Typically a large crawler must be disassembled at least into boom and cab and moved by trucks, rail cars or ships to its next location.
Floating cranes are used mainly in bridge building and port construction, but they are also used for occasional loading and unloading of especially heavy or awkward loads on and off ships. Some floating cranes are mounted on pontoons, others are specialized crane barges with a lifting capacity exceeding 10,000 short tons (8,929 long tons; 9,072 t) and have been used to transport entire bridge sections. Floating cranes have also been used to salvage sunken ships.
Crane vessels are often used in offshore construction. The largest revolving cranes can be found on SSCV Thialf, which has two cranes with a capacity of 7,100 tonnes (7,826 short tons; 6,988 long tons) each. For 50 years, the largest such crane was “Herman the German” at the Long Beach Naval Shipyard, one of three constructed by Nazi Germany and captured in the war. The crane was sold to the Panama Canal in 1996 where it is now known as Titan.
Crane Knowledge, Qualifications & Experience
Diesel Force have the knowledge, qualifications and experience to work on the following cranes ..
- Jib Cranes
- Davit Cranes
- Gantry/ Bridge Cranes
- Monorail Cranes
- Work Station Cranes
- Pick & Carry Cranes
- Portable Gantry Cranes
- Industrial Cranes
- Overhead Cranes
- As well as Truck Mounted Cranes such as ..
- Pole Borers
- Pressure Diggers
- Line Construction Trucks
- Specialty Equipment
Other Types Of Cranes
A reach stacker is a vehicle used for handling intermodal cargo containers in small terminals or medium-sized ports. Reach stackers are able to transport a container short distances very quickly and pile them in various rows depending on its access.
All Terrain Crane
An all-terrain crane is a hybrid combining the roadability of a truck-mounted and on-site maneuverability of a rough-terrain crane. It can both travel at speed on public roads and maneuver on rough terrain at the job site using all-wheel and crab steering.
AT’s have 2–12 axles and are designed for lifting loads up to 2,000 tonnes (2,205 short tons; 1,968 long tons).
Pick and Carry Crane
A pick and carry crane is similar to a mobile crane in that is designed to travel on public roads; however, pick and carry cranes have no stabiliser legs or outriggers and are designed to lift the load and carry it to its destination, within a small radius, then be able to drive to the next job. Pick and carry cranes are popular in Australia, where large distances are encountered between job sites. One popular manufacturer in Australia was Franna, who have since been bought by Terex, and now all pick and carry cranes are commonly called “Frannas”, even though they may be made by other manufacturers. Nearly every medium- and large-sized crane company in Australia has at least one and many companies have fleets of these cranes. The capacity range is between ten and forty tonnes (9.8 and 39.4 long tons; 11 and 44 short tons) as a maximum lift, although this is much less as the load gets further from the front of the crane. Pick and carry cranes have displaced the work usually completed by smaller truck cranes, as the set-up time is much quicker. Many steel fabrication yards also use pick and carry cranes, as they can “walk” with fabricated steel sections and place these where required with relative ease.
A sidelifter crane is a road-going truck or semi-trailer, able to hoist and transport ISO standard containers. Container lift is done with parallel crane-like hoists, which can lift a container from the ground or from a railway vehicle.
Carry Deck Crane
A carry deck crane is a small 4 wheel crane with a 360-degree rotating boom placed right in the centre and an operators cab located at one end under this boom. The rear section houses the engine and the area above the wheels is a flat deck. Very much an American invention the Carry deck can hoist a load in a confined space and then load it on the deck space around the cab or engine and subsequently move to another site. The Carry Deck principle is the American version of the pick and carry crane and both allow the load to be moved by the crane over short distances.
Telescopic handlers are forklift-like trucks that have set of forks mounted on a telescoping extendable boom like a crane. Early telescopic handlers only lifted in one direction and did not rotate; however, several of the manufacturers have designed telescopic handlers that rotate 360 degrees through a turntable and these machines look almost identical to the Rough Terrain Crane. These new 360-degree telescopic handler/crane models have outriggers or stabiliser legs that must be lowered before lifting; however, their design has been simplified so that they can be more quickly deployed. These machines are often used to handle pallets of bricks and install frame trusses on many new building sites and they have eroded much of the work for small telescopic truck cranes. Many of the world’s armed forces have purchased telescopic handlers and some of these are the much more expensive fully rotating types. Their off-road capability and their on site versatility to unload pallets using forks, or lift like a crane make them a valuable piece of machinery.
Dry bulk or container cranes usually in the bay areas or inland water ways.
A travel lift (also called a boat gantry crane, or boat crane) is a crane with two rectangular side panels joined by a single spanning beam at the top of one end. The crane is mobile with four groups of steerable wheels, one on each corner. These cranes allow boats with masts or tall super structures to be removed from the water and transported around docks or marinas. Not to be confused mechanical device used for transferring a vessel between two levels of water, which is also called a boat lift.
A railroad crane has flanged wheels for use on railroads. The simplest form is a crane mounted on a flatcar. More capable devices are purpose-built. Different types of crane are used for maintenance work, recovery operations and freight loading in goods yards and scrap handling facilities.
Aerial cranes or “sky cranes” usually are helicopters designed to lift large loads. Helicopters are able to travel to and lift in areas that are difficult to reach by conventional cranes. Helicopter cranes are most commonly used to lift loads onto shopping centers and high-rise buildings. They can lift anything within their lifting capacity, such as air conditioning units, cars, boats, swimming pools, etc. They also perform disaster relief after natural disasters for clean-up, and during wild-fires they are able to carry huge buckets of water to extinguish fires.
Some aerial cranes, mostly concepts, have also used lighter-than air aircraft, such as airships.
Instead of setting up a large crane to construct a wind turbine tower, a smaller climbing crane can help build the tower, climb with it to the top, lift the generator housing to its top, add the rotor blades, then climb down. This has been introduced by Lagerwey Wind and Enercon.
A Straddle carrier moves and stacks intermodal containers.
Exchanging mobility for the ability to carry greater loads and reach greater heights due to increased stability, these types of cranes are characterised by the fact that their main structure does not move during the period of use. However, many can still be assembled and disassembled. The structures basically are fixed in one place.
Ring cranes are some of the largest and heaviest land-based cranes ever designed. A ring-shaped track support the main superstructure allowing for extremely heavy loads (up to thousands of tonnes).
Tower cranes are a modern form of balance crane that consist of the same basic parts. Fixed to the ground on a concrete slab (and sometimes attached to the sides of structures), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. The base is then attached to the mast which gives the crane its height. Further, the mast is attached to the slewing unit (gear and motor) that allows the crane to rotate. On top of the slewing unit there are three main parts which are: the long horizontal jib (working arm), shorter counter-jib, and the operator’s cab.
Optimization of tower crane location in the construction sites has an important effect on material transportation costs of a project.
The long horizontal jib is the part of the crane that carries the load. The counter-jib carries a counterweight, usually of concrete blocks, while the jib suspends the load to and from the center of the crane. The crane operator either sits in a cab at the top of the tower or controls the crane by radio remote control from the ground. In the first case the operator’s cab is most usually located at the top of the tower attached to the turntable, but can be mounted on the jib, or partway down the tower. The lifting hook is operated by the crane operator using electric motors to manipulate wire rope cables through a system of sheaves. The hook is located on the long horizontal arm to lift the load which also contains its motor.
In order to hook and unhook the loads, the operator usually works in conjunction with a signaller (known as a “dogger”, “rigger” or “swamper”). They are most often in radio contact, and always use hand signals. The rigger or dogger directs the schedule of lifts for the crane, and is responsible for the safety of the rigging and loads.
Tower cranes can achieve a height under hook of over 100 metres.
Tower Crane Components
Tower cranes are used extensively in construction and other industry to hoist and move materials. There are many types of tower cranes. Although they are different in type, the main parts are the same, as follows:
Mast: the main supporting tower of the crane. It is made of steel trussed sections that are connected together during installation.
Slewing unit: the slewing unit sits at the top of the mast. This is the engine that enables the crane to rotate.
Operating cabin: on most tower cranes the operating cabin sits just above the slewing unit. It contains the operating controls, load-movement indicator system (LMI), scale, anemometer, etc.
Jib: the jib, or operating arm, extends horizontally from the crane. A “luffing” jib is able to move up and down; a fixed jib has a rolling trolley that runs along the underside to move goods horizontally.
Counter jib: holds counterweights, hoist motor, hoist drum and the electronics.
Hoist winch: the hoist winch assembly consists of the hoist winch (motor, gearbox, hoist drum, hoist rope, and brakes), the hoist motor controller, and supporting components, such as the platform. Many tower cranes have transmissions with two or more speeds.
Hook: the hook (or hooks) is used to connect the material to the crane. It is suspended from the hoist rope either at the tip, for luffing jib cranes, or in the hoist rope belly underneath the trolley for hammerhead cranes.
Weights: Large, moveable concrete counterweights are mounted toward the rear of the counterdeck, to compensate for the weight of the goods lifted and keep the center of gravity over the supporting tower.
Tower Crane Assembly
A tower crane is usually assembled by a telescopic jib (mobile) crane of greater reach (also see “self-erecting crane” below) and in the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will often be lifted to the roof of the completed tower to dismantle the tower crane afterwards, which may be more difficult than the installation.
Tower cranes can be operated by remote control, removing the need for the crane operator to sit in a cab atop the crane.
Tower Crane Operation
Each model and distinctive style of tower crane has a predetermined lifting chart that can be applied to any radii available, depending on its configuration. Similar to a mobile crane, a tower crane may lift an object of far greater mass closer to its center of rotation than at its maximum radius. An operator manipulates several levers and pedals to control each function of the crane.
Tower Crane Safety
When a tower crane is used in proximity to buildings, roads, power lines, or other tower cranes, a tower crane anti-collision system is used. This operator support system reduces the risk of a dangerous interaction occurring between a tower crane and another structure.
In some countries, such as France, tower crane anti-collision systems are mandatory.
Self-Erecting Tower Cranes
Generally a type of pedestrian operated tower crane, self-erecting tower cranes are transported as a single unit and can be assembled by a qualified technician without the assistance of a larger mobile crane. They are bottom slewing cranes that stand on outriggers, have no counter jib, have their counterweights and ballast at the base of the mast, cannot climb themselves, have a reduced capacity compared to standard tower cranes, and seldom have an operator’s cabin.
In some cases, smaller self-erecting tower cranes may have axles permanently fitted to the tower section to make maneuvering the crane onsite easier.
Tower cranes can also use a hydraulic-powered jack frame to raise themselves to add new tower sections without any additional other cranes assisting beyond the initial assembly stage. This is how it can grow to nearly any height needed to build the tallest skyscrapers when tied to a building as the building rises. The maximum unsupported height of a tower crane is around 265 ft. For a video of a crane getting taller, see “Crane Building Itself” on YouTube.
For another animation of such a crane in use, see “SAS Tower Construction Simulation” on YouTube. Here, the crane is used to erect a scaffold, which, in turn, contains a gantry to lift sections of a bridge spire.
Telescopic Tower Crane
A telescopic crane has a boom that consists of a number of tubes fitted one inside the other. A hydraulic cylinder or other powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are often used for short term construction projects, rescue jobs, lifting boats in and out of the water, etc. The relative compactness of telescopic booms makes them adaptable for many mobile applications.
Though not all telescopic cranes are mobile cranes, many of them are truck-mounted.
A telescopic tower crane has a telescopic mast and often a superstructure (jib) on top so that it functions as a tower crane. Some telescopic tower cranes also have a telescopic jib.
Hammerhead Tower Crane
The “hammerhead”, or giant cantilever, crane is a fixed-jib crane consisting of a steel-braced tower on which revolves a large, horizontal, double cantilever; the forward part of this cantilever or jib carries the lifting trolley, the jib is extended backwards in order to form a support for the machinery and counterbalancing weight. In addition to the motions of lifting and revolving, there is provided a so-called “racking” motion, by which the lifting trolley, with the load suspended, can be moved in and out along the jib without altering the level of the load. Such horizontal movement of the load is a marked feature of later crane design. These cranes are generally constructed in large sizes and can weigh up to 350 tons.
The design of Hammerkran evolved first in Germany around the turn of the 19th century and was adopted and developed for use in British shipyards to support the battleship construction program from 1904 to 1914. The ability of the hammerhead crane to lift heavy weights was useful for installing large pieces of battleships such as armour plate and gun barrels. Giant cantilever cranes were also installed in naval shipyards in Japan and in the United States. The British government also installed a giant cantilever crane at the Singapore Naval Base (1938) and later a copy of the crane was installed at Garden Island Naval Dockyard in Sydney (1951). These cranes provided repair support for the battle fleet operating far from Great Britain.
In the British Empire, the engineering firm Sir William Arrol Co Ltd was the principal manufacturer of giant cantilever cranes; the company built a total of fourteen. Among the sixty built in the world, few remain; seven in England and Scotland of about fifteen worldwide.
The Titan Clydebank is one of the four Scottish cranes on the River Clyde and preserved as a tourist attraction.
Level Luffing Crane
Normally a crane with a hinged jib will tend to have its hook also move up and down as the jib moves (or luffs). A level luffing crane is a crane of this common design, but with an extra mechanism to keep the hook at the same level when luffing.
An overhead crane, also known as a bridge crane, is a type of crane where the hook-and-line mechanism runs along a horizontal beam that itself runs along two widely separated rails. Often it is in a long factory building and runs along rails along the building’s two long walls. It is similar to a gantry crane. Overhead cranes typically consist of either a single beam or a double beam construction. These can be built using typical steel beams or a more complex box girder type. Double girder bridge are more typical when needing heavier capacity systems from 10 tons and above. The advantage of the box girder type configuration results in a system that has a lower deadweight yet a stronger overall system integrity. Also included would be a hoist to lift the items, the bridge, which spans the area covered by the crane, and a trolley to move along the bridge.
The most common overhead crane use is in the steel industry. At every step of the manufacturing process, until it leaves a factory as a finished product, steel is handled by an overhead crane. Raw materials are poured into a furnace by crane, hot steel is stored for cooling by an overhead crane, the finished coils are lifted and loaded onto trucks and trains by overhead crane, and the fabricator or stamper uses an overhead crane to handle the steel in his factory. The automobile industry uses overhead cranes for handling of raw materials. Smaller workstation cranes handle lighter loads in a work-area, such as CNC mill or saw.
Almost all paper mills use bridge cranes for regular maintenance requiring removal of heavy press rolls and other equipment. The bridge cranes are used in the initial construction of paper machines because they facilitate installation of the heavy cast iron paper drying drums and other massive equipment, some weighing as much as 70 tons.
In many instances the cost of a bridge crane can be largely offset with savings from not renting mobile cranes in the construction of a facility that uses a lot of heavy process equipment.
Electric Overhead Traveling Crane
This is most common type of overhead crane, found in many factories. These cranes are electrically operated by a control pendant, radio/IR remote pendant, or from an operator cabin attached to the crane.
A gantry crane has a hoist in a fixed machinery house or on a trolley that runs horizontally along rails, usually fitted on a single beam (mono-girder) or two beams (twin-girder). The crane frame is supported on a gantry system with equalized beams and wheels that run on the gantry rail, usually perpendicular to the trolley travel direction. These cranes come in all sizes, and some can move very heavy loads, particularly the extremely large examples used in shipyards or industrial installations. A special version is the container crane (or “Portainer” crane, named by the first manufacturer), designed for loading and unloading ship-borne containers at a port.
Most container cranes are of this type.
Located on the ships and boats, these are used for cargo operations or boat unloading and retrieval where no shore unloading facilities are available. Most are diesel-hydraulic or electric-hydraulic.
A jib crane is a type of crane where a horizontal member (jib or boom), supporting a moveable hoist, is fixed to a wall or to a floor-mounted pillar. Jib cranes are used in industrial premises and on military vehicles. The jib may swing through an arc, to give additional lateral movement, or be fixed. Similar cranes, often known simply as hoists, were fitted on the top floor of warehouse buildings to enable goods to be lifted to all floors.
Bulk-handling cranes are designed from the outset to carry a shell grab or bucket, rather than using a hook and a sling. They are used for bulk cargoes, such as coal, minerals, scrap metal etc.
A loader crane (also called a knuckle-boom crane or articulating crane) is an hydraulically powered articulated arm fitted to a truck or trailer, and is used for loading/unloading the vehicle cargo. The numerous jointed sections can be folded into a small space when the crane is not in use. One or more of the sections may be telescopic. Often the crane will have a degree of automation and be able to unload or stow itself without an operator’s instruction.
Unlike most cranes, the operator must move around the vehicle to be able to view his load; hence modern cranes may be fitted with a portable cabled or radio-linked control system to supplement the crane-mounted hydraulic control levers.
In the United Kingdom and Canada, this type of crane is often known colloquially as a “Hiab”, partly because this manufacturer invented the loader crane and was first into the UK market, and partly because the distinctive name was displayed prominently on the boom arm.
A rolloader crane is a loader crane mounted on a chassis with wheels. This chassis can ride on the trailer. Because the crane can move on the trailer, it can be a light crane, so the trailer is allowed to transport more goods.
A crane with a forklift type mechanism used in automated (computer-controlled) warehouses (known as an automated storage and retrieval system (AS/RS)). The crane moves on a track in an aisle of the warehouse. The fork can be raised or lowered to any of the levels of a storage rack and can be extended into the rack to store and retrieve the product. The product can in some cases be as large as an automobile. Stacker cranes are often used in the large freezer warehouses of frozen food manufacturers. This automation avoids requiring forklift drivers to work in below-freezing temperatures every day.
A block-setting crane is a form of crane. They were used for installing the large stone blocks used to build breakwaters, moles and stone piers.
Efficiency Increase Of Cranes
Lifetime of existing cranes made of welded metal structures can often be extended for many years by aftertreatment of welds. During development of cranes, load level (lifting load) can be significantly increased by taking into account the IIW recommendations, leading in most cases to an increase of the permissible lifting load and thus to an efficiency increase.
Similar Machines ..
The generally accepted definition of a crane is a machine for lifting and moving heavy objects by means of ropes or cables suspended from a movable arm. As such, a lifting machine that does not use cables, or else provides only vertical and not horizontal movement, cannot strictly be called a ‘crane’.
Types of crane-like lifting machine include:
Block and Tackle
A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.
The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load. The rope is threaded through the pulleys to provide mechanical advantage that amplifies the force applied to the rope.
A capstan is a vertical-axled rotating machine developed for use on sailing ships to multiply the pulling force of seamen when hauling ropes, cables, and hawsers. The principle is similar to that of the windlass, which has a horizontal axle.
A hoist is a device used for lifting or lowering a load by means of a drum or lift-wheel around which rope or chain wraps. It may be manually operated, electrically or pneumatically driven and may use chain, fiber or wire rope as its lifting medium. The most familiar form is an elevator, the car of which is raised and lowered by a hoist mechanism. Most hoists couple to their loads using a lifting hook. Today, there are a few governing bodies for the North American overhead hoist industry which include the Hoist Manufactures Institute, ASME, and the Occupational Safety and Health Administration. HMI is a product counsel of the Material Handling Industry of America consisting of hoist manufacturers promoting safe use of their products.
A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the tension of a rope or wire rope (also called “cable” or “wire cable”).
In its simplest form, it consists of a spool (or drum) attached to a hand crank. Traditionally, winches on ships accumulated wire or rope on the drum; those that do not accumulate, and instead pass on the wire/rope (see yacht photo above), are called capstans. Despite this, sailboat capstans are most often referred to as winches. Winches are the basis of such machines as tow trucks, steam shovels and elevators. More complex designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. It might include a solenoid brake and/or a mechanical brake or ratchet and pawl which prevents it unwinding unless the pawl is retracted. The rope may be stored on the winch. When trimming a line on a sailboat, the crew member turns the winch handle with one hand, while tailing (pulling on the loose tail end) with the other to maintain tension on the turns. Some winches have a “stripper” or cleat to maintain tension. These are known as “self-tailing” winches.
The windlass /ˈwɪndləs/ is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder (barrel), which is rotated by the turn of a crank or belt. A winch is affixed to one or both ends, and a cable or rope is wound around the winch, pulling a weight attached to the opposite end.
An aerial work platform (AWP), also known as an aerial device, elevating work platform (EWP), cherry picker, bucket truck or mobile elevating work platform (MEWP) is a mechanical device used to provide temporary access for people or equipment to inaccessible areas, usually at height. There are distinct types of mechanized access platforms and the individual types may also be known as a “cherry picker” or “scissor lift”.
They are generally used for temporary, flexible access purposes such as maintenance and construction work or by firefighters for emergency access, which distinguishes them from permanent access equipment such as elevators. They are designed to lift limited weights — usually less than a ton, although some have a higher safe working load (SWL) — distinguishing them from most types of cranes. They are usually capable of being set up and operated by a single person.
Regardless of the task they are used for, aerial work platforms may provide additional features beyond transport and access, including being equipped with electrical outlets or compressed air connectors for power tools. They may also be equipped with specialist equipment, such as carrying frames for window glass. Underbridge units are also available to lift operators down to a work area.
As the name suggests, cherry pickers were initially developed to facilitate the picking of cherries. Jay Eitel invented the device in 1944 after a frustrating day spent picking cherries using a ladder. He went on to launch the Telsta Corporation, Sunnyvale, CA in 1953 to manufacture the device. Another early cherry picker manufacturer was Stemm Brothers, Leavenworth, WA. Other uses for cherry pickers quickly evolved.
More technically advanced types of such lifting machines are often known as “cranes”, regardless of the official definition of the term.
Typical terms people use when searching for crane related services ..
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