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Quick couplers (also called quick hitches) are used with construction machines to allow the rapid change of working tools or buckets and attachments on the machine. They remove the need to use hammers to manually drive out and insert the mounting pins for attachments. They also bring with them additional safety risks that must be overcome by careful design and manufacture, and proper use.
Quick couplers are devices installed at the outer end of the work equipment of various types of construction and earth-moving machines. They facilitate the rapid exchange of working tools or buckets. Quick couplers are most common on hydraulic excavators and compact excavators and on the backhoe equipment of backhoe loaders, but are also installed on telescopic handlers, wheel loaders (loading shovels), skid-steer loaders and the loader equipment of backhoe-loaders. They are also occasionally installed on attachments installed on agricultural tractors. Quick couplers do not normally have a specific function themselves in that they do not carry out handling or digging operations, but when installed on a machine they become a part of the overall system. They are usually mounted on the machine by means of the pins that would otherwise be the mountings for the bucket or attachment. This article concentrates on quick couplers installed on excavators and similar equipment.
There are many variations in the design of quick couplers. The initial divergence is between those that can pick up any of a range of buckets and attachments by clamping onto the mounting pins for the attachment (known as "pin grabbers" or "pin couplers") and those that work only with buckets and attachments designed to suit that quick coupler (known as "dedicated"). The claimed advantage of pin-grabbers is flexibility in use in that a machine owner can use a variety of buckets and attachments without changing the quick coupler or buying an adaptor. The claimed advantages of dedicated couplers depend on their individual design but often include better performance and smaller size.
The method of operation (the picking up and releasing of buckets and attachments) causes the next divergence in design. The types can be described as manual, semi-automatic, and automatic.
Within the above three categories there are many further divergences in operating principles and detail designs. There are many competing claims relating to the safety and performance benefits and demerits of each design.
Fatalities have occurred due to buckets being accidentally released from work equipment during operation. Released buckets have hit bystanders causing fatal injuries. These have been reported in most detail in the UK, but there are reports of fatalities in Australia, [1] the Republic of Ireland and the USA.[ citation needed ] The causes of the fatal accidents are not always the same and the views of safety authorities in different countries differ on how to reduce risk. In the UK the Health and Safety Executive (HSE) analysed the accident data and concluded that all of the known fatalities were caused by the operator not inserting the safety pin in semi-automatic couplers. Even without the safety pin inserted the buckets would not have been released unless there had been a failure of some part of the mechanism, or some error in operation by the operator. The HSE concluded that the most effective way to reduce the risk of further accidents was for semi-automatic couplers to be withdrawn from sale. The suppliers of these couplers agreed to this voluntarily so semi-automatic couplers were withdrawn from sale in the UK by around October 2008. Safety authorities in other countries have taken a different approach. In Australia the authorities took the view that the problems were caused by designs of quick couplers that did not incorporate a safety pin. That is, they believe that semi-automatics are fundamentally safe. The Australian standard for quick couplers published by Standards Australia, AS 4774 - 2008 therefore does not exclude this design option. It is therefore obvious that the views of the safety authorities of the UK and Australia on what constitutes a safe design are very divergent. In the UK some major construction contractors have written their own specifications for quick couplers allowed on sites under their control. That is, they have pursued site safety via a procurement policy. An alternative approach has been put forward by the Strategic Forum Plant Safety Group. A working party under this group has drawn up a best practice guide that has been endorsed, inter alia, by the HSE. This provides an alternative route to site safety: adhering to best practice in the use of quick couplers.
The market for quick couplers is mainly supplied by a large number of small and medium-sized enterprises. Many of the manufacturers of quick couplers are small, flexible and innovative, leading to the wide variation in design concepts. Many Original Equipment Manufacturers (OEMs) of construction equipment market a range of quick couplers. Some of these are designed and manufactured by the OEM but more often they are the products of one of the quick coupler manufacturers branded by the OEM and sold through the OEM's distribution chain or installed by the OEM in their factory. In addition to the supply route from the OEMs many distributors of construction machinery will install quick couplers onto machines before delivery at the request of a customer. Quick coupler manufacturers will also sell direct to end-users and usually complete the installation as part of the sale.
A European standard in place since 1996 gives some guidance on the safety of quick couplers (EN474-1). However, this standard is unclear in many aspects leading to uncertainty as to whether semi-automatic couplers comply with it or not. Because of this the UK government launched a "safeguard action" under the Machinery Safety Directive (98/37/EC) challenging the validity of the standard and demanding that it be improved. The European Committee for Standardization (CEN) have therefore undertaken to revise the relevant section of the standard. Because of the divergence in design concepts and in opinions on how to manage the associated risks the International Organization for Standardization (ISO) has undertaken to draft an International Standard on the safety of quick couplers. This project is being undertaken by Technical Committee 127 (ISO TC/127). A Working Group was set up to draft the standard, which will be reviewed internationally through normal ISO procedures and will be published as ISO 13031. This work will probably be completed in 2013. The intention in Europe is that, subject to the standard being suitable, the ISO standard would then be adopted as the standard for Europe.
A valve is a device or natural object that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll.
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially tillage, and now many more. Agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
A skid loader, skid-steer loader, SSL, or skidsteer is any of a class of compact heavy equipment with lift arms that can attach to a wide variety of buckets and other labor-saving tools or attachments.
A shovel is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore.
A forklift is a powered industrial truck used to lift and move materials over short distances. The forklift was developed in the early 20th century by various companies, including Clark, which made transmissions, and Yale & Towne Manufacturing, which made hoists. Since World War II, the use and development of the forklift truck have greatly expanded worldwide. Forklifts have become an indispensable piece of equipment in manufacturing and warehousing. In 2013, the top 20 manufacturers worldwide posted sales of $30.4 billion, with 944,405 machines sold.
Excavators are heavy construction equipment consisting of a boom, dipper, bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression from the steam shovels and often mistakenly called power shovels, as power shovels may have similar looking buckets. All movement and functions of a hydraulic excavator are accomplished through the use of hydraulic fluid, with hydraulic cylinders and hydraulic motors. Due to the linear actuation of hydraulic cylinders, their mode of operation is fundamentally different from cable-operated excavators, which use winches and steel ropes to accomplish the movements.
A loader is a heavy equipment machine used in construction to move or load materials such as soil, rock, sand, demolition debris, etc. into or onto another type of machinery.
A backhoe—also called rear actor or back actor—is a type of excavating equipment, or digger, consisting of a digging bucket on the end of a two-part articulated arm. It is typically mounted on the back of a tractor or front loader, the latter forming a "backhoe loader". The section of the arm closest to the vehicle is known as the boom, while the section that carries the bucket is known as the dipper, both terms derived from steam shovels. The boom, which is the long piece of the backhoe arm attached to the tractor through a pivot called the king-post, is located closest to the cab. It allows the arm to pivot left and right, typically through a range of 180 to 200 degrees, and also enables lifting and lowering movements.
A backhoe loader, also called a loader backhoe, loader excavator, tractor excavator, digger or colloquially shortened to backhoe within the industry, is a heavy equipment vehicle that consists of a tractor-like unit fitted with a loader-style shovel/bucket on the front and a backhoe on the back. Due to its (relatively) small size and versatility, backhoe loaders are very common in urban engineering and small construction projects as well as developing countries. This type of machine is similar to and derived from what is now known as a TLB (Tractor-Loader-Backhoe), which is to say, an agricultural tractor fitted with a front loader and rear backhoe attachment.
Heavy equipment, heavy machinery, earthmovers, construction vehicles, or construction equipment, refers to heavy-duty vehicles specially designed to execute construction tasks, most frequently involving earthwork operations or other large construction tasks. Heavy equipment usually comprises five equipment systems: the implement, traction, structure, power train, and control/information.
A dragline excavator is a piece of heavy equipment used in civil engineering and surface mining.
A sidelifter is a specialised vehicle or semi-trailer used to hoist and transport ISO standard intermodal containers over longer distances.
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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", "boom lift" or "scissor lift".
A pile driver is a heavy-duty tool used to drive piles into soil to build piers, bridges, cofferdams, and other "pole" supported structures, and patterns of pilings as part of permanent deep foundations for buildings or other structures. Pilings may be made of wood, solid steel, or tubular steel, and may be driven entirely underwater/underground, or remain partially aboveground as elements of a finished structure.
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A jack is a mechanical lifting device used to apply great forces or lift heavy loads. A mechanical jack employs a screw thread for lifting heavy equipment. A hydraulic jack uses hydraulic power. The most common form is a car jack, floor jack or garage jack, which lifts vehicles so that maintenance can be performed. Jacks are usually rated for a maximum lifting capacity. Industrial jacks can be rated for many tons of load.
A tiltrotator is a hydraulic attachment/tool used on most excavators, and backhoes between 1,5 and 40 tons in the Nordic countries. A tiltrotator is mounted on the excavator such that the excavator bucket can be rotated through 360 degrees and one tilts +/- 45 degrees, in order to increase the flexibility and precision of the excavator. The Tiltrotator was introduced to the market in Sweden in the early 1980s by the Norgrens under the family owned and operated company named Noreco, and has become the standard in Scandinavia. The concept has recently gained popularity in other countries such as the Netherlands, Germany, UK, Japan, Canada and United States.
A bucket is a specialized container attached to a machine, as compared to a bucket adapted for manual use by a human being. It is a bulk material handling component.