Everything You Wanted To Know About Flexible Gear Couplings

Gear couplings are mechanical device used for power transmission and use a hub with gear teeth on the outer diameter of the input shaft. The hub on the output shaft is joined by a sleeve or flange with the teeth found in the inside diameter. This helps to transfer the torque as well as house shaft misalignment. Gear couplings are generally made of metals and so, they really need proper lubrication for a problem free running. These couplings are generally very rigid and can transfer high torque via small packages.

What does a coupling comprises of

Gear couplings consist of a clutch with an input connection to power take off and an output to transfer power input of trailer unit. The tension generated as the coupling joins the trailer units and tractor is generally monitored and the clutch slippage in also controlled in reaction to monitored tension. This monitoring is needed to regulate the speed of the trailer unit which is same as the speed of the tractor unit.

About flexible coupling

Flexible coupling joins rotating members like drive shafts and motors as well as allow misalignment in either parallel or angular offset orientation. These coupling types can be roller, block or silent chain. If you are looking for flexible couplings, here are mechanical considerations that you must look for:
- Rated speed
- Rated torque
- Backlash
- Torsional stiffness

Rated torque refers to the maximum service torque that rates the coupling, the rated speed refers to the maximum rated rotational speed of coupling, backlash is rotational position loss because of change in direction and stiffness is torque per unit angular deformation. The flexibility of such couplings prevent misalignment by moving the various parts of the coupling with negligible resistance.

Flexible gear coupling is able to pass on torques from 2,500 in-lb (208 ft-lb or 282 NM) to 47,269,000 in-lb (393,908 ft-lb or 533,462 NM) with an angular misalignment capacity of 3°.

Features of flexible gear couplings

Here are some of the usual features found in flexible gear couplings:

- Holds parallel, angular and axial misalignments
- Cost effective with good and long lasting performance and life
- Can absorb shock overloads as well as reduce shock due to starting torques
- Efficient in passing on power
- Made of forging materials along with meticulous machinery. So, these are easily inter-changeable.

Flexible gear coupling can give you trouble-free operation and these are independently installed equipments.

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Everything You Need to Know About Aerial Fiber Optic Cable Installation

Understanding The Basic Terms

Dead end pole: Dead end pole is a utility pole on which self-supporting figure 8 aerial cable or a steel messenger is tensioned and terminated into a dead-end fixture.



Messenger span: Messenger span refers to the length of continuous steel messenger tensioned between two dead-end poles.



Intermediate poles: Intermediate poles are all the poles between two dead-end poles.



Planning

Careful planning and preparation are necessary before any aerial cable installations. During the cable route survey, representatives from all necessary parties including utilities, street depart, etc should be present. Before even detailed planning begins, approval should be get from all involved parties. Sufficient clearance for new cable along the right of way should be confirmed during the route survey.



Existing poles should be used whenever possible in order to save cost.



Where on a pole to place the aerial fiber optic cable? Fiber optic cables weigh less than equivalent copper cables and also sag less, so fiber optic cables should occupy the uppermost available communications space on a pole.




Sufficient clearances must be maintained between fiber optic cables and electrical power cables on joint-use poles. You need to refer to current National Electrical Safety Code for the proper clearances.



Existing dead-end pole must be evaluated to see whether they can withstand the stresses during aerial cable installation. You have to evaluate whether temporary guying is needed in order to relieve the temporary unbalanced loading during cable installation.




Splice locations. Splice locations are usually selected during the cable route survey. They are chosen to allow for the longest possible continuous cable spans and a minimum number of splices. They should be easily accessible to a splicing vehicle.





Aerial installation should never be done in wet conditions. And make sure all personnel are properly trained for pole line work.


Fiber optic cables (including all dielectric cables) should be properly grounded when installed in the vicinity of high-voltage power cables.





Installation:

Fiber optic cable aerial installation can be done in two ways

Lashing a fiber optic cable to a steel messenger

A steel messenger is first installed between the poles. Then a cable reel trailer and truck are used to pull the cable along the messenger. A cable guide and cable lasher are used to wrap around both the messenger and the fiber cable to secure the fiber cable to the messenger. Following the cable lasher is an aerial bucket truck which makes necessary adjustments.

At each pole, the fiber optic cable forms an expansion loop to allow for expansion of the messenger. The expansion loop's sizes have both a length and a depth, its length should be larger than twice its depth. The fiber cable should also maintain its minimum bending radius at all times.

Direct installation of self-supporting figure 8 aerial fiber optic cables

Self-supporting (Figure-8) optical fiber cables greatly simplifies the task of placing fiber optic cables onto a aerial plant. The self-supporting figure-8 cable incorporates both a steel messenger and the fiber cable into a single jacket of Figure-8 cross section.

The combination of strand and optical fiber into a single cable allows rapid one-step installation and results in a more durable aerial plant.

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