Cranes and hoists

Duty types. S, S, and. S5 as discussed in Chapter 3 are normally applicable to crane and hoist motors. For duty types S4 and 5. the duty cycle per unit time is greater than S, . The most important factor is the number of switching operations per hour. A temperature rise in the motor occurs during acceleration, braking and reversing. 

Inspection by independent persons or bodies for safety purposes goes back to the middle of the nineteenth century. At that time, the focus of concern was the explosion of steam boilers, and this hazard was most prevalent in the textile industry. Consequently, a group of public-spirited individuals formed the Manchester Steam Users Association for the Prevention of Boiler Explosion. This body carried out boiler examinations and later added insurance as an inducement to the plant owners. By the beginning of the twentieth century steam and gas engines and electrical machines had been added, followed by lifts, cranes and hoisting machines. 

Tubular heat exchangers appear to have zero exponents, implyinig feftt direct labor cost is independent of size. This reflects the fact that s h equipment is set with cranes and hoists, which, when adequately sized for the task, recognize no appreciable difference in size of weight of the equipment. The higher labor exponent for installing carbon-steel towers indicates the increasing complexity of tower internals (trays, downcomers, etc.) as tower diameter increases. 

In supporting its proposed SEMS rule, MMS also discussed data on 1,443 Incidents that occurred over the same years, which involved 41 fatalities, 502 injuries, 10 losses of well control, 11 collisions, 476 fires, 356 pollution events , and 224 crane and hoist mishaps. It concluded that the majority of these incidents were related to operational and maintenance procedures or human error, and that operating procedures and mechanical integrity accounted for the greatest number of spills. 

The field and armature windings are connected in series and consequently share the same current. The series motor has the characteristics of a high starting torque but a speed which varies with load. Figure 2.47 shows series motor connections and characteristics. For this reason the motor is only suitable for direct coupling to a load, except in very small motors, such as vacuum cleaners and hand drills, and is ideally suited for applications where the machine must start on load, such as electric trains, cranes and hoists. 

The design of muck transport system must consider many other elements of the excavation. Crane and hoisted buckets, bucket elevator (conveyer belt), dumpers and car-hft, dumpers travelling on spiral road, muck pumping systems are commonly used mucking systems. 

Are cranes and hoist load limits labeled and legible Yes No N/A... 

Wire rope in cranes and hoists is inspected daily and before use. 1 2 3 4 N/A... 

Electrical Overhead Travelling (EOT) cranes and hoists (in process areas, in warehouses)... 

Yom local OHS legislation may include specific controls to be applied to certain types of plant, tools or equipment. These controls may specifically include the need for a person operating plant to be competent. There may be national certification standards for competency to operate, for example, cranes and hoists, and pressure vessels. Scaffolding and rigging may also be covered. Certain types of plant may need to be registered with a goverrunent authority. 

Conveyors, cranes, and hoists are generally considered fixed-path materials-handhng equipment, since they often become a fixed part of the physical plant. Once in place, a considerable amount of time, disruption, and cost is needed to change the arrangement of the equipment. It is therefore very important to plan the installation of these pieces of equipment very carefully. 

Variable Speed Variable-speed motors slow as the applied load is increased and speed up as the load is decreased. Applications include cranes and hoists. 

Conveyors - Reciprocating and shaker Cranes and hoists - Heavy-duty, logging, and rotary drilling Crashers... 

Fans — Centrifugal and light, small Cranes and hoists — Medium duty, skip Cranes and hoists — Heavy duty, including logging, lumbering, and... 

Regulations for crane and hoist signaling can be found in applicable American National Standards Institute (ANSI) standards. 

Mechanical handling techniques have improved efficiency and safety, but have introduced other sources of potential injury. Cranes and hoists, and powered trucks and fork-lifts are the primary means for mechanical handling on site. In all circumstances the safety of the equipment can be affected by the safety of operating conditions, site hazards and the operator. 

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