Grid Coupling: Parts, Application & Specification

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Couplings play a critical role in any industrial machinery configuration. As the point of connection between rotating shafts, they allow power to be transmitted to the gear reducer, converted into torque, and passed on to the machinery being driven. When chosen properly, the right couplings can even adjust for misalignments between connecting shafts. There are many different types of couplings available, selecting the right one depends heavily upon the application at hand as well as how the drive system is arranged. In this article, we will give a thorough answer to the question: “What is Grid Coupling?”. Follow this new blog in Linquip to find out the answer.

What is Grid Coupling?

Grid couplings are multi-piece mechanical shaft couplings used to transmit torque and rotation between shafts in mechanical power transmission assemblies. Their design allows them to accommodate the slight variations in alignment that occur between connected shafts, while also absorbing shock loads.

Grid Coupling Construction

A grid coupling consists of two shaft hubs, a metallic grid spring, and a split cover kit (which includes two cover halves, gaskets, seals, and hardware). Torque is transmitted between the two coupling shaft hubs through the metallic grid spring element. The split cover prevents the spring from being thrown under the action of centrifugal force. Lubricating oil exists inside the cover, which lubricating the contact between the spring and the tooth surface in case of dry friction.

The construction details of grid couplings are shown in the figure below.

The numbers in the figure above indicate different components of a grid coupling that are as follows.

1. Seal ring

2. Split cover

3. Hub

4. Spring

5. Sealing gasket

6. Bolt

7. Nut

8. Spacer

9. Oil plug

Grid couplings are available with either a horizontal or vertical split cover design. Horizontal covers are generally viewed as easier to install ( can be installed and removed at any time), while vertical covers enable a grid coupling to be run at a higher maximum speed and must be installed on the shafts before the coupling is put in place.

Grid couplings are also available in spacer and half spacer designs, which are ideal for allowing equipment to be serviced. Such designs are particularly popular in pump applications, where a drop-out section (full spacer design) or quick disconnect (half spacer design) allows for equipment servicing without disrupting the greased grid coupling element.

Grid Coupling Working Principle

The grid spring element absorbs impact energy by spreading it out over time, and thus reduces the magnitude of the peak loads. This is possible because of the progressive contact that occurs between the curved profile of the hub teeth and the flexible grid. As the load increases, more of the tooth comes into contact with the flexible grid spring element, thus supplying superior protection and supreme performance.

In light load application, the grid bears near the outer edges of the hub teeth. The long span between the points of contact remains free to flex under load variations. However, with the increase in load, the distance between the contact points on the hub teeth is shortened, but a free span remains to cushion shock loads. It must be noted that the coupling is flexible within its rated capacity. So under extreme overloads, the grid bears fully on the hub teeth and transmits the full load directly.

Grid Coupling Function

Grid couplings are capable of transmitting a significant amount of torque. They also have a unique ability to reduce vibration by as much as 30%, and cushion shock loads to safeguard driving and driven power transmission equipment.

Grid Coupling Application

Grid couplings are a popular coupling option where both high torque levels and dampening requirements exist. They are also used for medium- and heavy-duty torque transfer and should be considered along with gear couplings and disc couplings for such demanding applications. These couplings are well suited for shock loading applications and can take over for jaw couplings in pumping applications around 100 hp and up.

The horizontal split cover design grid couplings are suitable for reversing applications and limited space while the vertical design types are ideal for higher operating speeds and pump applications.

Grid Coupling Advantages

The main advantages of grid couplings are described below.

Ease of installation and maintenance reducing labor and downtime costs.
High tensile, shot-peened alloy steel grids and precision machined hubs ensure superior performance and long life.
The torsional flexibility and resilience of these grid couplings help reduce vibration and cushion shock and impact loads.
Cover fasteners can be provided in either Inch or Metric sizes.
Tapered grids are designed to be interchangeable with other industry-standard grid couplings with both horizontal and vertical grid covers.
Stock spacer or custom spacer lengths are available.
Excellent for use in applications where the equipment is close-coupled or spaced apart requiring a spacer style coupling arrangement.
When the grid needs replacing due to normal wear, it can be changed without disturbing the slotted hubs, so replacement of the grid is possible without moving machines and realigning them.

Grid Coupling Disadvantages

One of the biggest drawbacks of grid couplings is their limited ability to accommodate misalignment. While great at dampening vibration, they are not designed to handle parallel shaft misalignment and only designed to handle about half a degree of angular misalignment.

Additionally, grid couplings are also not maintenance-free because they require lubrication, which must be periodically checked and topped off if required. Care must also be taken to ensure that lubrication does not leak onto the ground and create an environmental concern.

So, now you know the answer to the question “what is grid coupling?”. If you enjoy this article in Linquip, let us know what you think by leaving a reply in the comment section. We will be more than glad to have your viewpoint on the article. Is there any question we can help you through? Feel free to sign up on our website where our experts are prepared to provide you with the most professional advice.

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