Cranes


Safe using of the various lifting machines like cranes, mine hoists, air rope ways, elevators etc. depends on steel wire ropes durability. Ropes are non repairable components of the machines. That is why the ropes worn or failed must be changed.  [c.334]

Scales can be portable so that they can be moved about and temporarily located where the weighing operation is to take place they may be light enough to be carried by hand, or they may be on wheels or be transported using a lift tmck. Even some tmck scales are considered portable because, for example, they are designed to be transported from one highway constmction project to another. Some scales are attached or built into portable material-handling devices such as cranes and lift tmcks, so that the weighing operation can take place while material is being transported.  [c.332]

Most limestone quarries use either 100% ammonium nitrate [6484-52-2] (fertilizer grade) and fuel oil (ANFO), or a combination of ANFO and ammonium or gelatin dynamite, for blasting (see Explosives and propellants, explosives). After blasting, oversized boulders usually are reduced to manageable sizes by drop ball cranes.  [c.169]

The American faciUties also differed fundamentally from the British faciUties in regard to maintenance philosophy. The American plants were designed to employ remote maintenance, ie, to remove and replace equipment using shielded cranes operating inside the shielded stmcture. The British developed a contact approach based on simplified designs for equipment downstream of the fission product removal step. The British approach has been used at all commercial faciUties.  [c.202]

Capacities of plastic dmms range from 9.5—208 L (2.5—55 gal) and the materials of constmction generally are polyolefins. Small plastic containers are often placed and transported inside of cormgated boxes for convenience in handling. Large containers, especially the 208-L (55-gal) variety, are designed to be handled by a wide range of materials-handling equipments, including hand tmcks, lift tmcks, and cranes.  [c.513]

Equipment-handling faciUties include any device used to convey or temporarily support equipment, or provide access for plant maintenance, eg, portable ladders, davits, A-frames, monorails, forklift vehicles, and cranes.  [c.69]

Bucket elevators, skip hoists, and cranes are used for top feeding of the furnace. Retention and downward flow are controlled by timing of the bottom discharge. Gases are propelled by a blower or by induced draft from a stack or discharge fan. In normal operation, the downward flow of sohds and upward flow of gas are constant with time, maintaining ideal steady-state conditions.  [c.1222]

Storage racks permit storing pallet loads of packages vertically as well as horizontally. Most pallet loads can be tiered two or three pallets high, with one resting on top of another (provided the packages are able to withstand the weight of the pallets above). Because me racks bear the pallet weight, stacks six to eight and even more pallets high are possible. Forklift trucks and stacker cranes are used to place and remove the pallets.  [c.1979]

These characteristics of wound-rotor motors determine their scope of application. They can accelerate very-high-inertia loads, such as crushers, by using a large external resistance to absorb the heat. Loads sensitive to shock-accelerating torques may also be accelerated softly by inserting a high starting rotor resistance this effect is used, for example, to t e up slack in gears. Wound rotors are also used to handle loads like punch presses and car crushers, for which extreme transient peak loads are supplied by the mechanical-system inertia, allowing the system to slow down during these peaks permanent external rotor resistance provides this soft characteristic. Wound-rotor motors are also used to provide adjustable-speed drives for pumps, cranes, and other loads when precise speed regulation is not required. Reduced-speed losses are not very significant for pump loads the percent efficiency is low at reduced speed, but the torque and load horsepower are dropping rapidly. If torque is proportional to speed squared, the maximum rotor-resistance losses never exceed 10.5 percent of the full-speed load (occurs at 70 percent speed and efficiency, 50 percent torque, 35 percent load horsepower, and 30 percent losses, thus 10.5 percent losses based on full load at full speed).  [c.2486]

Saturable reactors, which are adjustable by a small dc signal, have also been used for both primary (stator) and secondary (rotor) control. In the primary they control motor voltage and therefore torque. In combination with fixed secondary resistors and feedback from a tachometer, this system can be used for precise speed and torque control of cranes, hoists, etc. Even reversing can be accomplished by using two saturable reactors in each of two (of three) phases. Other combinations of fixed or saturable reac tors in the primaiy and/or secondaiy, all combined with secondary resistors, provide a wide range of capabiUties and flexibihty for the wound-rotor motor.  [c.2486]

Specific applications for such motors are rolling mills, rice mills, paper mills and cranes etc. for one or more of the following reasons  [c.20]

To meet the load demand for more frequent starts and reversals, as for cranes and other hoisting applications. f) To achieve the required speed variation through variation in rotor circuit impedance.  [c.20]

Likely applications are hoists, cranes and lifts.  [c.52]

Likely applications are hoists, cranes and rolling mills.  [c.52]

AC solenoid brakes These are employed for small motors, say, up to 15-20 h.p. They are suitable for applications such as conveyors, hoists, cranes, machine tools, lock gates and dumb waiters (Figure 6.53). The brakes are spring loaded and mounted on two mechanically opposing brake shoes. They grip a brake drum or disk, coupled rigidly at the NDE of the motor shaft. The brakes are applied mechanically and released electrically. The braking action takes place by deenergizing the spring. The brakes are normally applied in the OFF position for reasons of safety in the event of a power failure. They are released only when the solenoid is energized.  [c.151]

Electromagnetic shoe-brakes These are similar to the above, but are used for still higher motor ratings, say, 5-800 h,p. (Figure 6.54), In this ca,se instead of a solenoid coil, an electromagnetic coil is employed. This releases the brakes and develops a torque at least equal to the motor torque, to brake or hold the full load. In this case also, the brakes are applied on the motor shaft when the holding coil (electromagnet) is de-energized and is released only when the electromagnet is energized to make it safe against failure. Possible applications include cranes, hoists, elevators, conveyors, machine tools, rolling mills and ball mills, etc. and also holding of loads in conveyors, hoists and elevators, etc.  [c.152]

For most applications (e.g. cranes, lifts or machine tools) this factor is based on a loading of 0.5 or 0.75. This factor is also determined by the manufacturer and may have a shape as shown in Figure 6.66  [c.162]

Many crane manufacturers specify that the motor should be suitable for half an hour or one hour duration according to the British practice still followed in some countries. In fact, it is not possible to correlate precisely these ratings with any of the duty factors. Hence the motors are designed for any of the duty factors of 15%, 25%, 40% and 60%. In fact the duty factors for different types of cranes have been standardized, depending upon their operation, after several years of experience. For example, the cranes operated in steel industries have different types of duty factors as follows  [c.169]

Code of practice for safe use of cranes  [c.193]

Specification for power-driven mobile cranes  [c.193]

Specification for electrically driven jib cranes mounted on a high pedestal or portal carriage  [c.193]

Installations with only one operating ground (e.g., welding equipment, electrolysis grounds and dc cranes) can also produce stray currents if additional grounding at another place (e.g., a ground fault) is present. Stray currents can only occur with grounded equipment if two ground faults are present in different places at the same time.  [c.348]

In harbors, central dc supply equipment is still occasionally used as welding equipment on wharves, travelling dc cranes, dc supply for ships in dock, etc. In Ref. 1 proposals for avoiding stray currents are detailed in which separate dc supply equipment is stipulated. In ac distribution networks in which the subsequent dc network is grounded in only one place, there is no possibility that the dc currents will occur as stray currents.  [c.364]

Considerable stray currents can, of course, be caused by dc-driven cranes that load and unload ships where the rails act as the return conductor for the current. The rails run parallel to the harbor basin, quay walls of steel-reinforced concrete or steel piling walls. These can take up a large part of the stray current and conduct it further because of their small longitudinal resistance. Noticeable stray current inter-  [c.364]

During construction in the vicinity of overhead power lines, there is a great danger that construction equipment (e.g., cranes) may inadvertently come too close to the voltage-carrying conductor, causing arcing or even direct contact with the conductor cable. In both cases, dangerous contact voltages occur at the construction equipment itself and its surroundings. Great care should be taken in the construction and repair of pipelines to observe sufficiently wide distances for safety (see Fig. 23-2) [2-4].  [c.507]

The isolation of certain mechanical equipment, e.g. conveyors, work on lifts, excavations, entry and positioning of cranes, isolation of various safety services , e.g. water or inert gas, stand-by power generation, water supply to sprinkler systems, compressed air for breathing apparatus.  [c.419]

Overhead traveling cranes, hoists, and monorail systems  [c.56]

Because volume capacity of a semihulk package can range from 400 L (110 gal) to 3000 L (790 gal), having a net weight of 225—2270 kg, cranes, lift tmcks, and other powered materials-handling equipment are required for packaging and handling processes. Semibulk containers are either returnable or nonretumable. Returnable models generally are made of metal and maybe collapsible to minimize the cost of return shipment. Nonretumable semibulk containers tend to be constmcted of multiwall cormgated paperboard, typically with heavy gauge plastic liners, with pallets to faciUtate moving and handling. The choice of either type of container is based on economics and industry practice, since functionally satisfactory versions can be produced for either type.  [c.512]

With thek more ductile core, these steels are carburized to give a case hardness of 58—63 to a sufficient depth to accommodate the high rolling contact stress within the higher fatigue strength of the case-hardened material (40). Many automotive front wheel drive beatiags now use 52100 through-hardened steel and case-hardening alloys such as 1570. Large rolling beatiags for supportkig excavators, cranes, etc, employ heat-treatable steel of kicreased alloy content and 0.4—0.5% carbon. Thek raceway surfaces are frequendy gas carburized or kiduction hardened (41).  [c.9]

Copper matte, the molten copper and iron sulfides from the smelting furnace, is charged to the copper converters using large cranes and open ladles. Sihca flux is added to flux the iron in the matte. Air is blown into the charge through the tuyeres in the sides of the converters. The sulfides are oxidized to sulfur dioxide, which is collected in a hood and usually sent to sulfuric acid plants. The iron sulfide component in the matte is oxidized by blowing with air in the slag blow and combined with sihca to form iron sihcate slag, as shown in equation 15. In older plants, this slag may be returned to the reverberatory furnace to recover entrained and dissolved copper. Alternatively, the slag is processed by other means to recover copper, such as slow cooling and milling. After the slag has been poured off, further air in what is termed the finish blow provides oxygen to convert the copper sulfide to bhster copper, containing about 99% copper plus some sulfur, oxygen, and impurities (eq. 16—18). Figure 4 shows a typical converter. When the converter is rotated for charging and discharging, the air injection pipes,the tuyeres, are above the molten bath so that they are not blocked when the air is turned off. Partial blockages are cleared during blowing by use of mechanical tuyere punchers, steel bars that are periodically thmst through the tuyeres to dislodge any obstmctions.  [c.199]

Lift-truck operation is veiy simple and produc tive, even at 7-m (20-ft) elevations. Aisle racks can be as high as 30 m (100 ft), but above 7 m stacker cranes are favored over hft trucks because cranes allow seiwicing high storage at high rates. The installed investment in aisle racks, inclumng a stacker crane, is about 500 per pallet.  [c.1980]

Automatic Storage and Retrieval Systems These systems are of increasing importance in the warehousing of chemical products whether they are for consumer or industrial markets. They are comprised of warehouse racks which can be several stories high. These racks are serviced by stacker cranes equipped for palletized handling. Each rack is divided into storage modules. Each module is capable of holding one pallet load of product and has an address which is stored in a process control computer memory. Stacker cranes are under the direction of the process-control computer. Through use of bar codes marked on packages and pallets, products entering the warehouse are identified by such variables as nomenclature, weight, package type, and any expiration date. The entering pallet load is identified by its bar code through use of a laser scanner which picks up the information from the bar code and transmits it to the process-control computer. The computer then directs the stacker crane to an empty storage module which is available and makes a record of the product and its storage location. The stacker crane places the pallet load in the module. The computer verifies this record before the stacker crane leaves the storage module. Stacker cranes often are equipped with an enclosure for a person who can ride the crane and inspect any storage module. This is also used where an operator does order picking, as in the case when single cartons of product are ordered. The term papeiie.s.s wai ehou.se is a veiy apt description of automatic storage and retrieval systems since they rely entirely on bar code, scanning, and computers, with a minimum of personnel. Pallets for such systems must be accurately made to required dimensions and have sufficient mechanical strength to withstand the repeated handling. Often, metal pallets are used to support wood pallets and their loads. The metal pallets never leave the warehouse, and assure trouble-free operation.  [c.1980]

Typical applications for adjustable-voltage, adjustable-speed dc drives include winders, paper machines and auxiliaries, blending systems, feeders, extruders, calendars, machine tools, range and slasher drives, cranes, hoists, shovels and draghnes, and an almost unhmited variety of drives requiring the flexibility and efficiency possible with direct current.  [c.2487]

I In both the above types of braking systems, a hand-operated device is also provided, to release the mcehanieal brakes in applieations such as lifts, elevators, cranes, and winders. This  [c.152]

Specification tor power driven overhead travelling cranes, semi-goliath and goliath cranes for general use  [c.193]

Applications include electric motor drives for conveyors and other material handling equipment such as stacker reclaimers, crushers, haulages, ball mills, cranes, hammer mills, rotary dryers, centrifuges, reciprocating pumps, winches, fans and wire drawing machines.  [c.199]

Steel works conveyors, crushers, w agon tipplers, skid gears, furnace charges, bogie drives in bogie hearth furnaces, furnace winch drives, cranes, pumps, compressors and fans.  [c.200]

Due to their very narrow operating range, these relays have limitation in their application on drives with fluctuating loads such as cranes, hoists or pole changing motors, or loads with intermittent duties with frequent variations in the load current. In view of a generally wide voltage fluctuation on an LT distribution network, even a definite duty motor may have cognisable current variations, leading to unwanted trippings of the machine.  [c.286]

Gas turbines usually come packaged in their own enclosures. These enclosures are designed so that they limit the noise to 70dB at a 100ft (30 meters) from the gas turbine. In the case of a combined cycle power plant consisting of the gas turbine, HRSG, and the steam turbine can be either inside or outside. While open plants are less expensive than enclosed plants, some owners prefer to enclose their steam turbines in a building and use permanent cranes for maintenance. Thus leaving the gas turbine and the HRSG in the open environment. In severe climate areas, the entire plant is enclosed in a building. Single-shaft combined cycle power plant with the generator in the middle require a wider building to allow the generator to be moved to facilitate rotor removal and inspection. Plant arrangements that do not use axial or side exhaust steam turbines result in a taller building and higher building costs.  [c.147]

Other Items is considered for this discussion to be a catchall category including everything else. Cranes and other mobile equipment, product storage, and holding ponds are some examples. Again, the operating company needs to take the lead in making sure the list is complete enough for the cost estimate accuracy required. The cost estimators cannot be expected to design the plant.  [c.229]

Lists of mechanical equipment available, e.g. diggers, cranes, lifting equipment, and of emergency supplies, e.g. sand, wood, sandbags, drainseals, pipeblockers and absorbents for spillages on the ground and in drainage systems floating booms for immiscible liquids (s.g. <1.0) that enter waters, and skimmers.  [c.426]


See pages that mention the term Cranes : [c.271]    [c.271]    [c.444]    [c.89]    [c.863]    [c.863]    [c.2487]    [c.169]    [c.533]   
What went wrong (0) -- [ c.33 ]

Plant Engineer's Handbook (2001) -- [ c.0 ]