Flat belt drives

Figure 8.10 Angle of contact with a flat-belt drive...

These are short centre drives unlike flat belt drives. The belt slip in such drives is negligible. The recommended maximum power that can be transmitted through such belts of different cross-sectional areas is provided by the belt manufacturer. The normal cross-sections of V belts in practice are given in Table 8.3. The cross-section of a belt depends upon the power to be transmitted and its speed. To select the appropriate section of the belt for the required transfer of load refer to Figure 8.11 also provided by the manufacturer. It is recommended that... 

Direct-connected, geared, chain, V-belt, or flat-belt drive. 

Flat belts, one of the earliest forms of flexible power transmission, are generally more suited to high-speed, low-horsepower applications. At low speeds and high loads, flat-belt drives usually become too large to be cost-effective. 

Propeller Fa.ns, Propeller fans may have from 2 to 6 blades mounted on a central shaft and revolving within a narrow mounting ting, either driven by belt drive or directiy coimected. The form of the blade ia commercial units varies from a basic airfoil to simple flat or curved plates of many shapes. The wheel hub is small ia diameter compared to the wheel. The blades may even be mounted to a spider frame or tube without any hub. The housiag surrounding the blades can range from a simple plate or flat ring to a streamlined or curved beU—mouth orifice. 

The flat belt is a friction drive transmitting load through the friction between the belt and the pulley while the V-belt is a positive drive which is flat on one side and has a projection like a geartooth on the other. These... 

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. 

Belt conveyors come in a wide variety of forms. The simplest form is a flat belt conveyor, which is often roller supported (i.e., there is a series of rollers placed underneath the belt). Belt conveyors are typically driven by a drive puUey/roUer connected to an electric motor. For conveying items that may not be containerized, however, belt conveyors can also be of the slider-bed-supported type, where a flat metal surface is placed underneath the belt. An everyday example of the sUder-bed supported belt conveyor can be found at the check-out lanes of most grocery stores. 

Belt drives are usually chosen for their simplicity and low cost. They cire not positive drives, as are some of the alternatives discussed below, but will allow up to about 3% slippage (belt drives should Bierefore not be used with synchronous motors). Flat belts in particular have some limitations in speed and in their ability to transfer power. 

Belt drives basically fit into four types flat, V, V-ribbed, and synchronous. Although each of these basic belt types are more suitable in specific application areas, most applications can be successfully designed with more than one type of belt. 

The problems of high tension with flat belts led to the development of V belts. Unlike flat belts, which depend only on friction, V belts have deep V-shaped cross sections that wedge into the sheave groove to provide added horsepower capacity. Because of the wedging action, V belts are highly stable and can operate at tensions considerably lower than those needed by flat belts. Thus, V-belt drives can be more compact and allow for smaller shafts and bearings. 

V-belt drive, flat-belt, chain, and gear drives, in accordance with NEMA standards... 

Drives is the term given to power-transmission equipment. The simplest form of power transmission is a belt drive. A belt drive can have a flat, V-belt, ribbed belt, or toothed belt design. These drives are common in applications such as conveyors. Conveyor manufacturers should be consulted for their catalogues on power-transmission capability. 

Uses of flat conveyor and (power) transmission belts and V-belts (for power transmission) are to be found in almost all major industries. V-belts for different types cover applications ranging from fan belts for automobiles, belts for low-power drives for domestic, laboratory, and light industrial applications, to high-power belts for large industrial applications. 

Belt conveyors are very versatile and the most widely used. They can convey loose or packaged loads over short or long distances, horizontally, or up and down gradual slopes. The endless belts, which are either flat or curved, run over rollers and between pulleys. The drive pulley usually is placed at the delivery or highest end to keep the belt taut. The materials most commonly used for conveyor belts are rubber, plastic, or leather. 

Carboxylated nitrile rubber (XNBR) has better abrasion resistance than regular NBR. Their applications are automotive seals, industrial footwear, mechanical goods, textile spinning cots, adhesives, packings, flat drive belting, hoses, industrial wheels, oil well specialties, and roll covers. 

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