The construction of gear couplings, it seems to me, would be a type that would create a basically dc force when misaligned. These gear couplings are distinguished by their mechanical flexibility and compensation of angular, parallel and axial. High performance gear couplings lovejoy a timken company. The lovejoy coupling handbook introduction the goal of this handbook is to assist you with the process of sorting out the myriad of coupling styles that exist to select the one best suited to your application. Types g20, gv20 type g large gear coupling spacer couplings for pump and compressor applications simplify servicing connected equipment. Compared to spur or helical gears, it is more difficult to inspect gear accuracy of. Alignment it is not the intention of this post to detail the means and methods for aligning gear couplings, which is a much bigger subject.
Spacer couplings use a standard double engagement coupling with a spacer. Shaft alignment tolerances historically, shaft alignment tolerances have been governed by the coupling manufacturers design specifications. The e420 consists of a display, m movable unit and s stationary unit. Although alignment is covered in another section of this handbook, the gear coupling has some special alignment considerations that should be noted here. The gear coupling does have some alignment considerations that should be noted. This means that longer periods between relubrication. The type g large gear coupling is available in all types for capacities up to 72,450,000 lbin, 8,185,000 nm. Alignment can be checked on the precisionmachined flanges using only a straightedge and calipers. Short flex tolerances express the misalignment as an angle between the shaft centerlines and as the offset between the shaft centerlinesprojected to the coupling center. Consider all values listed to be the maximum allowable deviation from the alignment target, be it zero or some desired value to compensate for. Tolerances based on rpm and coupling spacer length were first.
Proper tooth contact is one of the elements in providing gear accuracy and very important for bevel gear and worm gear pairs. The single joint allows for minor misalignments such. Before installing this coupling on any system containing sleeve bearings, herringbone gear sets or other devices sensitive to axial thrust. Select a gear coupling to connect a 500 hp, 1170 rpm electric motor. Customer modifications and alterations to the coupling are not permissible. This wear rate is heavily influenced by lubrication and the type. I used easylaser e420 to do the alignment of cooling tower motorgearbox. Gear couplings belong to the category of flexible couplings that are capable of transmitting very high torques. Maintenance in the hpi what causes wear in geartype couplings. Installation and maintenance instructions atraflex. Coal handling plant alignment standards for shaft to shaft. Vibraligns recommended shaft alignment tolerances are based on acceptable tolerances used by industry and should be used in place of coupling tolerances when no alignment tolerance is specified by a companys engineering or reliability department. Machinery alignment tolerance tables impact engineering. Machinery alignment tolerance tables the suggested alignment tolerances shown here are general values based upon experience and general industry standards and should not be exceeded.
A gear coupling is a mechanical device for transmitting torque between two shafts that are not collinear. High number of coupling bolts failures, coupling bush failures, gear teeth of coupling failures or they wear quickly. The two joints are connected by a third shaft, called. As mentioned in the bolting section, it is necessary for the two halves of flanged type to have some sort of piloting for best alignment practice. Coupling is the device used to join two shafts say, the driver and the driven to transmit power. The original function of a flexible coupling was to. Unless otherwise agreed, hub bore tolerance j7, keyways to din 6885 and keyway width tolerance js9. Gear coupling permits parallel, angular misalignments and end floating by crown gear teeth. Alignment tolerances specify how close the pump and driver shaft centerlines should be to collinear at running conditions. If a manufacturer of a machine or coupling require tighter alignment tolerances, those should be used. Gear mesh misalignment gear solutions magazine your.
The useful life of a geartype coupling is limited by the rate of wear of its teeth. Select the coupling size that has a maximum bore capacity equal to or larger than the larger of the two. The lovejoy coupling handbook lovejoy a timken company. The coupling may only be used in accordance with the technical data provided in the falk steelflex coupling catalog. Clearance and interference coupling fits efficient plant. Is there an iso doc tell it or some industrial tradition. When using shortflex coupling tolerances, the centerline of rotation of each machine is aligned at the coupling center, which is the center between the flex planes, or average center of power of.
We dont think you should waste time on rough alignment either and thats why our engineers designed the stealth series laser shaft alignment systems with dualbeam and dualfan technology. Vibraligns recommended shaft alignment tolerances are based on acceptable tolerances used by industry and should be used in. Single joint gear couplings are used to connect two nominally coaxial shafts. Are coupling manufacturer tolerances good enough for shaft. It consists of a flexible joint fixed to each shaft. The typical failure mode of gear couplings is that the teeth wear away from improper lubrication andor excessive misalignment until there is excessive backlash and tooth tip clearance. However, many companies offer alignment tolerances. A typical geartoothstyle steel coupling couplings for connecting shafts shown. When gear couplings are mounted on a horizontal floating shaft, use a gap disc in each coupling. Excessive amounts of grease or oil on the inside of the coupling guard.
The performance and the life of the gear coupling depend on how you install and service them. Most coupling manufacturers alignment tolerances are based on the amount of misalignment the coupling will tolerate before failing. Gear mesh misalignment may result in shifts in the load distribution of a gear pair that results in increasing contact and bending stresses, moving the peak bending stresses to the edge of the face. Using shortflex coupling tolerances on spacer couplings. A practical guide to shaft alignment plant services. For most highspeed gear couplings, an expensive filter and.
Since it is not practical to consider all these variables in a reasonably useful alignment specification, some simplification of tolerances is necessary. Laser alignment of cooling tower motorgearbox shaft youtube. Major diameter fit gear teeth, precision machined tolerances, and high quality components help to reduce the potential unbalance in the coupling assembly. A coupling alignment tolerance and a shaft alignment tolerance are different things very different things. For example, the only correct way to express shaftalignment tolerances is in terms of alignment conditions at the coupling, and we will describe several ways to do this. Some mechanics measure alignment quality using the coupling manufacturers recommendations. Installation and maintenance instructions falk steelflex. In this application the device is called a geartype flexible, or flexible coupling.
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