A universal joint lets a ratchet drive a socket that is not in line with it, which is often the difference between reaching a fastener and removing half an assembly to get at it. This is the complete list of 7, by drive size.
What a universal joint costs you
A single universal joint does not transmit rotation evenly. At an angle, the output speed rises and falls twice per revolution even though the input is steady, and torque varies inversely with it. At small angles this is unnoticeable. Past about thirty degrees it becomes a pulsing you can feel through the ratchet, and it puts a cyclic load into the joint pins that is what eventually wears them out. Keep the angle as small as the job allows rather than as large as the joint permits.
Keeping it under control
An unloaded universal joint flops, so the socket wanders off the fastener exactly when you are working blind. Two things fix it: start the socket on the fastener by hand before picking up the ratchet, and support the joint with a finger while you take up the slack. Once the fastener is loaded the joint straightens itself under torque and behaves. A short extension between the joint and the socket also helps, because it gives you somewhere to hold.
All 7 universal joints
| Drive size | Type | Teng part number | EAN |
|---|---|---|---|
| 1/4 in | Chrome | M140030-C | 5020385130043 |
| 3/8 in | Chrome | M380030-C | 5020385130258 |
| 1/2 in | Chrome | M120030-C | 5020385130562 |
| 1/2 in | Impact | 920030AN | 5020385126114 |
| 1/2 in | Impact | 920030N | 5020385126435 |
| 3/4 in | Chrome | M340030-C | 5020385138872 |
| 3/4 in | Impact | 940030-C | 5020385123953 |
Where this list comes from
Every row is read from the live Teng Tools USA catalogue on the day this page was generated — product record, part number and size taken from the record itself, never transcribed from a printed catalogue or inferred from a pattern. Impact-rated joints are identified from the product record and marked in the type column; they are not interchangeable with chrome joints in use. A size that has been discontinued disappears from this list rather than lingering as a part number you cannot order, which is the failure mode of every static spec sheet.
Universal joint or wobble extension
They solve overlapping problems differently. A wobble extension allows a few degrees of misalignment at the socket end while the bar itself stays essentially in line, so it keeps most of the feel and all of the control — it is the right answer for a fastener that is nearly in line. A universal joint allows a genuinely large angle and gives up feel to do it. Reach for the wobble first; a joint is for when the ratchet and the fastener are pointing in different directions.
Joints and bars are in sockets and accessories; impact-rated equivalents are in impact sockets.