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What is Coupling? How to install it?

flange flexible coupling
Before we get to what a coupling (can be replacement of Lovejoy coupling)is, we have to first understand the basics.
Let us see them in the below order:

  • What is coupling?
  • What are the types of couplings?
  • How is coupling size determined?
  • Lovejoy coupling คืออะไร?
  • How is Lovejoy coupling installed?

What is coupling?

Wikipedia explains that coupling is a device used to connect two shafts together at their ends to transmit power.
Couplings do not normally allow disconnection of shafts during operation, however, there are torque limiting couplings which can slip or disconnect when some torque limit is exceeded. Selection, installation and maintenance of couplings can lead to reduced maintenance time and maintenance cost.

It mainly helps in the transmission of power while also providing an angle that serves the purpose of movement.
So four key things are provided by couplings

  1. Power transmission usually from a bigger rotating device to a smaller device thereby increasing the speed of rotation
  2. Movement of the coupled parts in a beneficial direction. For example, in a car, it can be the forward or reverse movement of the vehicle
  3. Increased control on the speed, torque, the power delivered and cutoff on exceeding limits
  4. Better control over maintenance time and cost – thereby, improved productivity

Now let’s try to understand the next question we had:

What are the types of coupling?

The following are the main types of coupling we have

  • Jaw couplings – In this type of coupling – two jaws are connected and an elastomeric spider or a rubber-based connecting piece is placed between them to help with the transmission of torque via compression of the material used. Such couplings flex element is mostly made of NBR, polyurethane, Hytrel or Bronze. They usually accommodate misalignment, transmit torque, help in dampening of vibration and low torque, general-purpose applications.
  • Sleeve couplings – They are used for transmitting low to medium torque between connected equipment via an elastomeric insert with male splines that mate with female hub splines. The insert material is typically EPDM, Neoprene or Hytrel and the insert can be a one or two-piece design. They help in moderate misalignment, Torsional or twisting movement-based dampening of vibration, have an end float with slight axial clearance and are used for low to medium torque, general-purpose applications
  • Tire couplings – These couplings too have a rubber or polyurethane element connected between the two hubs. The rubber element transmits torque via a shear and reduces transmission of shock loads or vibration. This type of coupling has higher misalignment capacity and is easy to assemble without many moving hubs or connected equipment. This type of coupling supports high-speed operations and provides a wide range of torque capacity.
  • Disc coupling – A disc coupling’s main principle of operation is that torque is transmitted through the flexing disc elements. It operates via the alternating tension and compression of segments on a common bolt circle joined alternately between the driving and driven sides. These couplings consist of two hubs, two discs packs, and a centre member. A single-disc pack can accommodate angular and axial misalignment. Two-disc packs are usually needed to accommodate parallel misalignment. This is a true limited end float design with zero-backlash or impact on the devices. Hence, it provides high-speed control/rating and better balance to the entire setup.
  • Diaphragm Coupling – They utilize a single or a series of plates called as diaphragms, as the flexible members. It helps in the transmission of torque from the outside diameter of a flexible plate to the inside diameter, across the spool or spacer piece, and then from inside to outside diameter. This deflection of the outer diameter relative to the inner diameter is what occurs when the diaphragm is subject to misalignment. For example, axial displacement attempts to stretch the diaphragm which results in a combination of elongations and bending of the diaphragm profile. This allows for angular, parallel and high axial misalignments. They are mostly used in high torque, high-speed applications.
  • Gear Couplings – Gear couplings transmit the highest amount of torque and the highest amount of torque in the smallest diameter of any flexible coupling. These couplings have a service life of 3 to 5 years and in some cases, they can last for decades. Grid couplings consist of 2 radially slotted hubs that mesh with a serpentine strip of spring steel the grid provides torsional damping and flexibility of an elastomer but the strength of steel. Grid couplings transmit torque and accommodate angular, parallel and axial misalignment from one hub to the other through the rocking and sliding of a tapered grid in the mating hub slots. The grid cross-section is generally tapered for better hub contact and easier assembly. As there is movement between contacting hub and grid metal parts, lubrication is required. Roller Chain type couplings consist of two radially sprocketed hubs that engage a strand of double pitch roller chain. Chain couplings are used for low to moderate torque and speed applications. The meshing of the sprocket teeth and chain transmits torque and the associated clearances accommodate angular, parallel and axial misalignment. Chain couplings require periodic lubrication depending on the application. The lubrication is typically brushed onto the chain and a cover is used to help keep the lubrication on the coupling.

Now let’s try to understand the next question before we get to the topic, finally:

How do you determine coupling size?

The first step is to understand the requirement correctly.

We will have to map out the dimensions – misalignment required and the torque capacity needed.

Some of them are very large in diameter for the amount of torque that they’re transmitting and then some of them are relatively small.

One point to remember when you’re selecting a coupling is that there’s no governing body for couplings and how they’re rated. So couplings need to be tested for the requirement and used based on performance.

So read the specifications carefully. There could be dynamic torque couplings and there could be static torque couplings.

Finally, reaching the topic at hand:

Lovejoy coupling คืออะไร?
ข้อต่อ Lovejoy เป็นข้อต่อชนิดขากรรไกรที่ใช้งานได้หลากหลายสำหรับงานเบาไปจนถึงมอเตอร์สำหรับงานหนักที่ใช้ในระบบส่งกำลังไฟฟ้า

นี่เป็นผลิตภัณฑ์ประเภทหนึ่งที่ปลอดภัยที่สุดของเรา สาเหตุที่ข้อต่อเหล่านี้ทำงานได้แม้ว่ายางจะล้มเหลวและไม่มีการสัมผัสระหว่างโลหะกับโลหะ

They perform in well-standing oil, grease, moisture, sand, and dirt and nearly 850,000 bore combinations that can be customised as per the customer’s needs.


Types of Lovejoy couplings

According to the size chart, the types of Lovejoy coupling are numerous.

The important types of jaw coupling are straight tooth jaw and curved tooth-jaw couplings.

The straight tooth jaw couplings are attached to elastomers to prevent friction between other components and for the smooth functioning of the motor or any other device.
The straight-tooth jaw couplings are fail-safe, and curved tooth jaw couplings are not.
The price is lower in comparison to the high power delivery they do.
A straight jaw coupling supports radially removable elastomers, and hence these are very easy to assemble and require less maintenance.

A curved jaw coupling has zero-backlash and is used in devices that operate on stop and go principles.
These are used in high power motors and generators. For example, if a timer is set to take high-resolution pictures, then the curved jaw coupling can help with the different periods to trigger the photography mechanism.
These couplings are highly used in equipment where the accuracy required is very high.

Specifications of Lovejoy couplings

  • L-type or standard jaw coupling
  • AL-Type Jaw Coupling
  • SS-Type Jaw Coupling
  • SW
  • LC
  • RRC
  • C-Type
  • H-Type

Functions of Lovejoy coupling

Main functions are:

● General-purpose power transmission coupling used in generators, motors and other power transmission devices
● Also used in motion control or servo applications
● Connects duty electric pieces of machinery like generators, motors, and gearboxes.
● Prevent friction between the components and ensure smooth or better functioning of the product.
● Intended to transmit torque between two shafts by connecting them using elastomer and dampen the system vibrations to prevent friction between other components.
● Easy to install and maintain
● Operate in various temperatures and climatic conditions
● Affordable and fail-safe
● Work even if the elastomers or spiders fail
● We recommend replacing the spiders periodically
● Steel and bronze elastomers last for longer durations but are costlier
● Support the efficient functioning of an engine or a motor
● Resistant to chemical reactions and friction
● Efficiently handle misalignments and load while providing a good life for electronic devices or return on investment. They are usually dirt proof, and moisture-proof and thereby, have longer life spans
● Great speed capability

How to install a Lovejoy coupling?
Here are the steps to do the installation but be sure to first follow all safety measures and disconnect devices from the power source
1. Identify the objects, disconnect them and keep them spread out in the open
2. Match the coupling size to the shafts
3. Check for snug fits before mounting the hubs
4. Slide the appropriate hubs into place
5. If using a spider, insert it first
6. Move the equipment into the proper locations
7. Check alignment using either “straight edge method” or a dial indicator
8. See if cushions are to be inserted between the jaws in each hub
9. Using a calibrated torque wrench tighten the set screw into the hubs
10. Recheck for axial, parallel and angular alignments for accuracy
11. Remove any tooling or other material away
12. Connect back to power and see if the operation is smooth at various speeds

That brings us to the end of the post. Hope you have better information now on couplings, their types, a Lovejoy coupling and on how to install it.

Feel free to browse through our extensive coupling product list – https://www.ever-power.net/product-category/coupling/

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