Crane Scales
Used predominantly in industries where items must be moved as well as weighed, crane scales serve a dual purpose. In addition to providing the weight measurements of a given load, crane scales act as a safety feature, ensuring that operators do not mistakenly overload the crane. These weighing mechanisms can be stationary or
portable scales, depending upon the needs of the application. Industries that make frequent use of this particular type of
scale include construction, fishing, shipping, metal handling, aviation, batching, foundry, agriculture and more. While the cranes are a common scene on worksites or in factories and warehouses for each of these applications, the scale itself may be less noticeable and even detachable for use only in some functions of the crane. Although the strength of the crane is reflected in the capabilities of the scale; the hooks, chains and other apparatus used to hold an attached load must also be made of durable materials. These often include steel, stainless steel and cast iron. The metal used as well as the specific crane design have a significant impact on the rate loads of a scale; some cranes are capable of lifting and weighing up to ten tons of material.
The loads to be weighed may be attached directly to the hook point of a crane or affixed via the use of chains, trays or other apparatus. J-hooks, S-hooks and various clips are used for strength and reliability. No matter the type of hook, platform or other container, the weight reading must be adjusted for the additional materials. The dial or digital screen should read zero when no items are placed on the hook or scale, accounting for the weight of the equipment. Dial scales accomplish this by rotating the lever at the back of a unit or turning a special tool in a slot behind the gauge.
Digital scales feature what is known as a "tare" function that deducts the weight of the holding container. The selection of analog or digital displays depends largely on budget and the exact needs of an industry. All older hanging scales and a great deal of modern crane scales use dial scales. This is a more cost effective option that needs no external power source, is easy to read and provides accurate measurements. These function through the use of metal coils or springs with pre-calculated and consistent resistance. The change in degree of compression as the spring is pulled down by the attached load corresponds to a particular weight. The dial rotates to align with this weight on the scale as the spring is extended. The drawback of spring based dial crane scales is the inability to measure with precision. Digital scales on the other hand can offer readings accurate to a fraction of a gram if needed. These scales use digital sensors that convert deformation into electrical signals that are either stored in a computer or shown on an LCD screen, which may be attached or wireless.
