Level luffing crane

I want to introduct something about AVL & PBL Products. We can supply all kinds of AVL tubes & PBL tubes,and we also supply AVL film & PBL fil A level luffing crane is a crane mechanism where the hook remains at the same level whilst luffing; moving the jib up and down, so as to move the hook inwards and outwards relative to the base.Some types of crane are inherently level luffing: those with a fixed horizontal jib, such as gantry, hammerhead or the fixed-jib tower cranes commonly used in construction. Usually though, the description is only applied to those with a luffing jib that have some additional mechanism applied to keep the hook level when luffing.Level luffing is most important when careful movement of a load near ground level is required, such as in construction or shipbuilding. This partially explains the popularity of fixed horizontal jibs in these fields.Contents1 Toplis cable luffing 2 Horse-head jibs 3 Powered level luffing 4 Luffing cabs 5 Meccano models 6 References // Toplis cable luffingStothert & Pitt crane with Toplis gearAn early form of level luffing gear was the "Toplis" design, invented by a Stothert & Pitt engineer in 1914. This is also a purely mechanical linkage, arranged by the reeving of the hoist cables to the jib over pulleys at the crane's apex above the cab, so that luffing the jib upwards allows more free cable and lowers the hook to compensate.Horse-head jibsHorse-head designThe usual mechanism for level luffing in modern cranes is to add an additional "horse head" section to the top of the jib. By careful design of the geometry, this keeps level merely by the linked action of the pivots.Powered level luffingAs cranes and their control systems became more sophisticated, it became possible to control the level of luffing directly, by winching the hoist cable in and out as needed. The first of these systems used mechanical clutches between luffing and hoist drums, giving simplicity and a "near level" result.Later systems have used modern electronic controls and quickly reversible motors with good slow-speed control to the hoist winch motors, so as to give a positioning accuracy of inches. Some early systems used controllable hydraulic gearboxes to achieve the same result, but these added complexity and cost and so were only popular where hgih accuracy was needed, such as for shipbuilding.Luffing cabsLuffing mechanisms have also been applied to the driver's cab being mounted on its own jib, following the movement of the crane's main jib These are used for tasks such as ship unloading, where the view from the driver's cab is greatly improved by cantilevering it forwards and over the ship.Meccano modelsCranes have long been a popular subject for Meccano models, and luffing cranes are no exception. References^ "Level luffing crans" (pdf). Konecranes. http://www.konecranes.com/attachments/brochures/level_luffing_low.pdf. ^ "Dockside crane: Stothert and Pitt's DD2". Design 1968 Journal. 1968. http://vads.ahds.ac.uk/diad/article.php?year=1968&title=233&article=d.233.47. ^ a b "Toplis level luffing crane". http://www.btinternet.com/~a.esplen/models/pic12.htm. ^ Molian, Samuel (1982). Mechanism Design: An Introductory Text. CUP. p.p61. ISBN 0521231930. ^ Convertible level luffing crane USpatent3685668 ^ Double link level luffing crane USpatent4606469 ^ Joseph N. Attard. "Level luffing crane model". http://www.patbelford.com/toys/library/level-luffing-crane/index.html. ^ "Level Luffing Port Crane" (pdf). South East London Meccano club. http://www.selmec.org.uk/Downloads/article_0008_level_luffing_port_crane.pdf. v?d?eTypes of CranesContainer crane Crane vessel Gantry crane Level luffing crane Sidelift Straddle carrier Tow truckCategories: Cranes Mechanical engineering stubs(and so on) To get More information , you can visit some products about power factor meter, military webbing, . The AVL & PBL Products products should be show more here!