Different U-Joint Sizes Explained (2024)

Different U-Joint Sizes Explained

Once you've understood the purpose of u-joints, you'll need to use other classifying factors to find the proper one for your job. Identifying the type of u-joint will also be determined by the application in which it will be used. After having thedifferent u-joint sizes explained,you will be able to decide on the best joint for the project at hand.

Before finding the universal joint you need for your job, you will need to know some essential facts. Sizing coincides with the type of machine you are implementing the joint into. It’s beneficial to understand what these joints do and their purpose, along with types of joints and how to measure them. Understanding u-joint body types will aid in the decision-making process for the products you choose. Following a few general pointers or even speaking with a professional can help shed light on these key elements.

What Are U-Joints

Universal joints, or u-joints, are used to allow driveshafts to move with the suspension. They ensure that power can be transferred from the transmission and drive-wheels without breaking. U-joints are typically placed at either end of a driveshaft, allowing for the transfer of mechanical energy between two moving parts. This leaves both parts room for flexibility without harming or breaking vital components within machinery. In vehicles, the u-joint is a cross-shaped piece in between two yokes.

Purpose

The purpose of a universal joint is to allow the movement of driveshafts simultaneously with the machine's suspension. U-joints permit the axes to be at an angle from each other. It compensates for the fact that the driveshaft isn't necessarily always in-line with the component that it’s connected to. If the driveshaft is between a stationary object and a moving one, a u-joint would be needed to allow free movement between those items.

U-joints can be located along driveshafts, 4WD transfer case shafts, and even axle shafts. U-joints are different from constant velocity joints. They are consistently under immense pressure and friction that can wear out without proper lubrication. Operating at improper angles or abnormal conditions are contributing factors in deterioration. Rough vibrations or odd sounds such as clunking or squeaking of the driveshaft may indicate an impending u-joint failure.

Some Common Types of U-Joints

Hooke-Type Joint: a universal coupling that connects axes to rigid rods commonly used in the transmission of rotary motion.

Double-Hooke-Type Joint: similar to constant velocity, the double-Hooke joint involves two Hooke's joints with a shaft in the middle to help eliminate discrepancies in the angular dislocation and velocity between driving and driven shafts.

Birfield Joint: a 100% true constant velocity (CV) joint. Dissimilar to the function of a u-joint where vibrations and spinning unequal transfer amounts of power, the Birfield joint creates an even and steady transfer rate of torque.

Understanding U-Joint Sizes

Understanding what size of universal joint you need for your job requires knowing many things. If deciding on the u-joints for a vehicle, keep in mind that different makes of cars and trucks require different sized u-joints.DriveShaft of Tulsaoffers extensive information on how to identify u-joints as well as comprehensive information ondriveshaft services. Measuring joints will help you identify the proper u-joint size and type.

How To Measure U-Joints

Most universal joints will have one side that is pushed into the welded-in yoke, while the other side connects to the other yoke. C-clips are used to hold the pressed in caps of the u-joint in place. When measuring a universal joint, you will need to see if it is an inside or outside-locking joint.

Most of the time, these u-joints are not interchangeable, so you'll need to identify which type you require. They will be measured in different ways. You may use a tape measure, but a digital caliper can be more efficient and accurate, as well as more time effective. Refer to outside and inside-locking u-joint charts to help determine the series you are working with:

Measuring Inside-Locking U-Joints: To obtain the proper length of an inside locking u-joint, measure from groove to groove.

Measuring Outside-Locking U-Joints: To obtain the proper length of an outside locking u-joint, measure from cap end to cap end.

Two Types of U-Joint Bodies

There are two types of universal joint bodies, solid-body or non-greaseable, the latter of which is often referred to as "lubed for life" as they do not contain grease fittings. They do not have stress risers by the opening of the fitting, deeming them stronger. Greaseable joints must be lubricated regularly. People often fail to routinely grease the greaseable joints, which should be lubricated at least every 5,000 miles.

There is a lot of disagreement amongst tradespeople on whether the non-greaseable joint is indeed stronger than its greaseable counterpart. Of course, something that doesn't require routine maintenance always seems to be a better candidate for lasting life and staying intact longer. However, there is not a lot of evidentiary support to prove it. Some companies make a grease fitting at the end of the joint cap rather than in the body to make greasing easier and less invasive.

Making the decision about whether to go with the greaseable or non-greaseable joint depends on how honest you are with yourself about your commitment to maintaining your driveshaft. Asking yourself how often you'll grease your driveshaft will be necessary if you're leaning toward a greaseable joint. If you know that you won't be greasing your driveshaft routinely, opt for the non-greaseable joint, as it is better sealed than a greaseable joint. Non-greaseable joints are also designed to resist grease, dirt, and water infiltration.

No joint lasts forever. Knowing how to maintain your joint in order to get the most life out of it is important. Some decisions about your joint are in your control. Other choices may depend solely on where the joint is being used and what it is being used for. By following this basic guide ofdifferent u-joint sizes explainedas well as other key features about them, you'll be better educated and more prepared to complete your project.

This is a general guide, and there is always more to learn about the different types of u-joints. If you are unclear at any time, ask a professional. They will be able to determine the necessary next steps regarding both products and procedures accompanied with machinery that requires a driveshaft and universal joints.

Connecting Multiple U-Joints

The major advantage of selecting universal joints instead of other types of couplings is their ability to compensate for greater angular misalignments while transmitting relatively high torques. Read on to learn more about connecting multiple u joints.

Single U-Joint Operating Angles

Single U-Joints can compensate for angular misalignment of up to 45 degrees between the input and output shaft. In some very specific cases, this angle can be increased even further, but this is not recommended for use with any significant rotational speed.

The angle can also be increased by attaching multiple universal joints in line. However, each additional joint requires a support to limit the degrees of freedom and ensure the proper transmission of torque and motion. Additional U Joints and supports add friction and thus reduce the efficiency of the power transmission chain.

Typically, the connection of 2 single Joints is the most common variant of sequenced joints. A user can either connect two single joints by pinning or welding the hubs together or use a single center component, also called a ‘double yoke’, eliminating the need for additional machining, welding, and assembling.

Depending on size and type of Joint, these center components are available as part of the standard product range or are made to order. For some less popular sizes, manufacturers revert to the connection of 2 single U Joints with the aforementioned methods.

Double U-Joint Operating Angles

Double universal joints cannot only increase the operating angle going around a corner (sometimes referred to as "W configuration"), they also allow for the compensation of parallel misalignment between driving and driven shaft (a “Z configuration”).

U-Joints in correct W and Z configuration on a virtual plane

U-Joints in incorrect W and Z configuration on a virtual plane

Conditions For Connecting Universal Joints

Both configurations offer nearly constant velocity between the ingoing and outgoing end of the joint.

However, a few conditions must be met. The double joint must be located on a virtual plane and the operating angles of the two joints must be the same. If one or both joint ends are placed at an angle that takes the assembly from the virtual plane into a free 3D configuration, the constant velocity relation is lost. Also, the two joints need to be phased at 180° against each other, aligning the inwards pointing yokes.

U-Joints not on a virtual plane

U-Joints with correct and incorrect phasing

Constant Velocity Of A U-Joint

Constant velocity refers to both joint ends rotating at the same speed and remaining at the same point of revolution at all times. This is not the case for a single universal joint. At a constant input speed, the output side of the joint rotates at a fluctuating speed wave with speeds different at various points of the revolution. The amount of the fluctuation is related to the operating angle. The higher the angle, the more the speed / position of the output shaft differs from the input shaft. Depending on the application and operation conditions, this can lead to positioning errors or vibrations.

U-Joint Rotation Angle Difference

Due to the increased friction from the double joints and the sequential setup of the joint centers, it is recommended that the torque ratings for a double joints are reduced by 10% compared to a single joint of the same design and size. However, in many cases the use of a double joint can increase the lifetime of the configuration. Especially for friction bearing joints, the transmittable torque decreases swiftly with increasing angle. A reduction in operating angle per joint by using a double universal joint in w configuration can reduce bearing stress and provide constant velocity operation of input and output shaft.

Interested In Our Universal Joints?

Catalog Download

Request a Quote

Universal Joint: Definition, Working Principle, Applications, Advantages, Disadvantages

What is Universal Joint?

A universal joint, also known as a U-joint, is a type of mechanical coupling that allows two shafts to be connected and transmit torque while still being able to rotate freely and move in different directions. This is achieved by using two yokes, each attached to one of the shafts, and a cross-shaped connecting piece called a cross-pin that links the two yokes together. The cross-pin is mounted in bearings in the yokes, allowing it to rotate and swivel, allowing the shafts to move and rotate relative to each other.

Universal joints are commonly used in various applications, such as drive shafts for vehicles, machinery for industrial processes, and other mechanical systems where the flexible and versatile coupling is needed. The universal joint diagram is given below.

Working Principle of Universal Joint

The working principle of a universal joint is based on using two yokes, each attached to one of the shafts to be coupled, and a cross-shaped connecting piece called a cross-pin that links the two yokes together. The cross-pin is mounted in bearings in the yokes, allowing it to rotate and swivel, allowing the shafts to move and rotate relative to each other.

When torque is applied to one of the shafts, it is transmitted through the universal joint to the other shaft, causing it to rotate. As the relative orientation of the two shafts changes, the cross-pin can rotate and swivel in the bearings in the yokes, allowing the universal joint to accommodate these changes while transmitting torque and allowing the shafts to rotate. This allows the universal joint to provide a flexible and versatile coupling between the two shafts, allowing them to move and rotate freely in different directions while transmitting torque.

Types of Universal Joints

There are several different types of universal joints, which vary in their design and application. Some common types of universal joints include

Single Cardan joint: This is the most common type of universal joint, and it consists of a single cross-shaped connecting piece that links the two yokes together. This allows the joint to accommodate changes in the relative orientation of the two shafts while transmitting torque and allowing them to rotate.

Double Cardan joint: This type of universal joint consists of two cross-shaped connecting pieces arranged in series, which link the two yokes together. This allows the joint to accommodate even larger changes in the relative orientation of the two shafts, and it is often used in applications where the shafts may be subjected to more extreme movements.

Constant velocity joint: This type of universal joint is designed to maintain a constant rotational velocity between the two shafts, even as their relative orientation changes. This is achieved by using a series of small balls or rollers that are arranged specially, allowing the joint to accommodate changes in orientation while maintaining a constant velocity.

Hooke's joint: This type of universal joint uses a series of curved arms, or levers, to link the two yokes together. This allows the joint to accommodate changes in orientation while transmitting torque and allowing the shafts to rotate.

Cross and bearing joint: This type of universal joint uses a cross-shaped connecting piece and a series of bearings to link the two yokes together. This allows the joint to accommodate changes in orientation while transmitting torque and allowing the shafts to rotate.

Applications of Universal Joints

Universal joints are commonly used in various applications due to their ability to accommodate changes in the relative orientation of the two shafts that are coupled together while transmitting torque and allowing them to rotate. Some common applications of universal joints include

In drive shafts for vehicles, such as cars, trucks, and tractors, the shaft must be able to accommodate changes in orientation as the vehicle moves over uneven terrain.

Machinery for industrial processes, such as conveyor belts, mixers, and other equipment, may require shafts that can move and rotate in different directions.

In power transmission systems, such as those used in wind turbines, the shafts may be subject to large and varying forces, requiring a flexible and versatile coupling.

In robotics, universal joints are often used to connect the different parts of a robot's body, allowing it to move and rotate freely.

In other mechanical systems where flexible and versatile coupling is needed, such as in cranes and other lifting equipment, marine propulsion systems, and various other applications.

Advantages of Universal Joints

Universal joints have several advantages over other mechanical couplings, making them useful in various applications. Some of the main advantages of universal joints include

Flexibility: Universal joints can accommodate changes in the relative orientation of the two coupled shafts, allowing them to move and rotate freely in different directions. This makes them ideal for applications where the shafts may be subject to large and varying forces or need to move and rotate in different directions.

Versatility: Universal joints can transmit torque and allow the shafts to rotate, making them useful for a wide range of applications where power transmission or rotation is needed.

Compactness: Universal joints are relatively small and compact, which makes them easy to incorporate into a wide range of mechanical systems.

Durability: Universal joints are typically designed to be robust and durable, with high-quality bearings and other components that can withstand large forces and long-term use.

Cost-effectiveness: Universal joints are generally less expensive than other types of couplings, which makes them an economical choice for many applications.

Disadvantages of Universal Joints

While universal joints have many advantages, they also have disadvantages. Some of the main disadvantages of universal joints include

Limited range of motion: Universal joints can only accommodate a limited range of changes in the relative orientation of the two coupled shafts. This means they may not be suitable for applications where the shafts may be subject to large or extreme movements.

Loss of power: Due to how universal joints are designed, some power is lost as the torque is transmitted through the joint. This means that the shafts may not rotate as efficiently as they would if coupled using a different type of coupling.

Noise and vibration: Universal joints can sometimes produce noise and vibration as the shafts rotate, which may be undesirable in some applications.

Maintenance: Universal joints require regular maintenance and lubrication to function properly and to maintain their durability and performance. This can add to the overall cost and complexity of using universal joints in some applications.

Get complete information about the GATE exam pattern, cut-off, and all those related things on the BYJU’S Exam Prep official youtube channel.