Power transmission chains

Power transmission chains provide a positive drive even when operated under very adverse temperatures (-60 to 600°F) and other environmental conditions. These pow er transmission systems are very flexible with regards to their field applications. In general, chain drives are primarily selected for low-speed and medium-speed service. Some silent chain designs may be used in high-speed serv ice [8,13]. 

The dynamics of power transmission chain drives are not conducive to high-speed operation. Since proper installation requires some looseness in the chain, they tend to separate from the sprockets at higher speeds. In general, transmission chains are limited to a maximum sprocket speed of 3,600 revolutions per minute (rpm). 

Leaf chains Leaf chains are usually not considered to be power transmission chains (see Figure 58.28). Instead, they are most often used in applications, such as hoisting... 

Standard double-pitch roller chain uses the same pins and bushings as standard single-pitch roller chain, but the pitch of the hnk plates is twice that of single-pitch chain. The link plates for doublepitch power transmission chain have a figure-eight shape. This is so they can clear the hub of small sprockets. The rollers for these chains are the same as those for standard single-pitch chains. Doublepitch power transmission chain is shown in Figure 2-9. 

Link-Suspended Basket Centrifuges In centrifuges with diameters larger than 762 mm (30 in), the basket, curb, curb cover, and drive form a rigid assembly flexibly suspended from three fixed posts (also known as a three-column centrifuge). The three suspension members may be either chain hnks or stiff rods in ball-and-socket joints and are spring-loaded. The suspended assembly has restrained freedom to oscillate to compensate for a normal out-of-balance condition. The drive is vertical with more efficient power transmission compared to the base-bearing type. 

In nearly all mechanical power applications in the oil and gas industry it is necessary to transmit the power generated by a prime mover to an operation (e.g., drawworks of a drilling rig, or a production pumping system). The transmission of rotary power to such operation elements is carried out by a power transmission system. Mechanical power transmission is typically carried out by power betting systems, chain systems, gear systems and by hydraulic systems, or some combination of these three [1,5]. 

There are six types of chains used for power transmission. These are roller, silent (inverted tooth), offset link (Ewart with bushing), detachable (open Ewart), pintle (closed Ewart), and bead,... 

Some of these are shown in Figure 3-26. Because most modern power transmissions use roller chains, silent chains or the offset link (Ewart) chains, these will be the only chain types discussed since they are quite important in oil field applications. 

There are design considerations for the various chain power transmission applications that are common to nearly all chain types [8]. These are discussed in the following. 

Faulkner, L. L., and Menkes, S. B., Chains for Power Transmission and Materials Handling Marcel Dekker, New York, 1982. 

Heavy Duty Offset Sdebar Power Transmission Roller Chain andSprocket Teeth, A N.SIStaftdiard B g9.1. 29.10M-I981. ... 

Chain-drives normally are used to provide positive power transmission between a driver and driven unit where direct coupling cannot be accomplished. Chain-drives generally have two distinct running speeds driver or input speed and driven or output speed. Each of the shaft speeds is clearly visible in the vibration profile and a discrete narrowband window should be established to monitor each of the running speeds. 

There are two types of flexible intermediate drives used to transmit torsional power belt drives and chain drives. Flexible belts are used in industrial power transmission applications primarily when the speeds of the driver and driven shafts must be different or when the shafts must be widely separated. The trend toward higher speed primary drivers and the need to achieve a slower, useful driven speed are additional factors favoring the use of belts. In addition to V-belts, there are round belts and flat belts. Chain drives are typically used in applications where space is limited or obstructions prevent direct coupling of machine-train components. 

This section is an overview of flexible drive chains and sprockets. It provides the basic knowledge required to install, operate, and service this means of power transmission. 

Drives such as pumps, fans, blowers, and many other types of machinery commonly employ silent chains as their prime source of power transmission. Because of their unique design, silent chains provide the most positive means of traction. Because of this, they often are used in important applications such as timing drives on critical equipment. 

Chains for Power Transmission and Material Handling Design and Applications Handbook, American Chain Association... 

In the preamble it has already been mentioned that about 3 % of the energy for propulsion are required for the supply of the on-board systems. Looking at the entire power supply chain from the kerosene tank via the pump to the engine, the transmission, the generators, etc. to the consumers at, the calculated efficiency is approximately 40 %, while in the case of H2-FPEM chain an efficiency of 47.5 % could be achieved [1]. 

The drive sprocket is injection-moulded in rubber-toughened PA6.6, which is resistant to repeated impact over a wide range of temperatures, and which shows excellent abrasion resistance. The plastic sprocket absorbs the shock of gear changes better than metal, causes less wear on the chain, and provides a quieter ride. The polymer is resistant to lubricants and other liquids. Reduced firiction improves power transmission and, coupled with a lower weight, results in better performance. 

Figure 2 shows the FTA of this function and all the blocks that participate in the error of not energizing the balise. The maximum responsible for this error are all the components in the transmission chain, the power detector and the power supply. 

Power transmission apparatus functions as the part of the mechanical system that transmits energy to the part of the machine performing the work. These components include flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, cranks, and gears. 

Another kind of hazard is getting caught in a machine or tool. Many people have experienced the pinching action of a pair of pliers. One can get caught in many ways. Power transmission elements, such as belts, chains, gears, linkages, shafts, and other components, have pinch points or catch... 

Most machines use power transmission components to transfer power from a motor, engine or other prime mover to an element of a machine where a useful function occurs. Some common power transmission components are belts, pulleys, ropes, sheaves, chains, sprockets, gears, and friction rollers. Many of these components create pinch, nip, or shear points. 

Belts, gears, shafts, pulleys, sprockets, spindles, drums, fly wheels, chains, or other reciprocating, rotating, or other moving parts or equipment shall be guarded if such parts are exposed to contact by employees, or otherwise create a hazard. Guarding shall meet the requirements of the American National Standards Institute B 15.1-1958 Rev., Safety Code for Mechanical Power Transmission Apparatus. 

The functional uses of styrenic block copolymers are usually a result of the unique characteristics of these types of synthetic polymers, related to the nature of the block segments covalently linked in the polymer chain to the nature of the energetic interactions between the chain segments, or to the network stucture that is achieved in combinations where the block copolymer has multiple hard blocks in each chain. The functional utility of the block copolymer is to provide a specialized and vital function to the whole without imparting the "rubber identity to the whole. For example, the rubber seals in a power transmission device are vital to the operation of the transmission, yet there is no identity imparted to the transmission by the rubber gaskets and seals. A rubber which is added to a thermoplastic or thermoset to provide a mechanism of impact resistance has a functional use rather than a monolithic structural use even though that is the function of the plastic. 

Chain drives do not require pre-tension between shafts for power transmission, thereby reducing bearing loads. 

Roller chain drives are used in a wide range of power transmission applications for all basic industries such as food processing, materials handling, oil field equipment, construction, agricultural equipment, and machine tools. 

Fourteen standard sizes of single- and multiple-width roller chain are listed in ANSI Standard B29.1 (American National Standards Institute, New York see Figs. 5.82 and 5.83. Table 5.17 shows the chain number, corresponding pitch size, and the ANSI minimum ultimate tensile strength for single-width chain. This standard includes those roller chains that are intended for use in power transmission and conveying applications. These chains are not intended for use in overhead hoists or lifting applications. For specific information on hoist and leaf chains, see ANSI B29.24 and B29.8, respectively. 

The result was that the industry soon became known as the precision roller chain industry. Efforts to standardize, beginning as early as 1913, led to the precision roller chain industry being one of the first in the world to have published standards available to designers and others concerned with roller chains. The basic series of roller chains—precision power transmission roller chains—were the first roller chains to be covered in an American National Standard, ASME B29.1 (then ASA B29a) in 1930. Since then, several varieties of roller chains have been standardized, and they will be covered in subsequent chapters of this book. 

It is only in the past few decades that certain raigineering steel chains have been standardized so that recognized standards could be issued. The first engineering steel chains to be covered by an ANSI standard were heavy-duty offset sidebar power transmission roller chains (ASME B29.10). That was soon followed by standards covering steel bushed roUa-less chains (ASME B29.12) and... 

The major uses of the four types of chain fisted above are in drives (power transmission), conveyors, bucket elevators, and tension hnkages. Each of these applications is discussed in detail in subsequent chapters. Some standard chains are designed for use in only one of these application. However, some chains are designed so that they can be adapted to more than one use. 

The B29 series of the American National Standards, covering chains, attachments, and sprockets for power transmission and conveying, were designated as ANSI B29.xx standards for many years. Recently, however, ANSI and ASME agreed that the standards developed by ASME would be designated simply as ASME standards, and did not need to carry the ANSI prefix. All B29 standards are developed by ASME and approved by ANSI as American National Standards, but now they are designated simply as ASME B29.xx standards. 

There are three types of standard power transmission roller chain ... 

ASME B29.3 standard double-pitch power transmission roller chain, shown in Figure 2-8. 

In the power transmission field, standard roller chain applications range from fractional horsepower drives to those requiring in excess of 1000 hp. The V4-in. pitch chains, weighing less than 2 oz./ft., have been applied to such intricate machines as microfilm projectors. On the other hand, large-pitch multiple-strand chains, weighing over 50 Ib./ft., meet the requirements of such heavy-duty service as oil field equipment (Figure 2-9). 

Double-pitch power transmission roller chains are particularly applicable to power drives where speeds are slow, loads are moderate, or center distances are long. For such applications, the longer pitch results in a lighter and less expensive chain. 

Now let us consider the advantages of chains from the standpoint of drives. Chains have certain advantages, in addition to those just named, over other types of power transmission equipment. 

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