Left hand trhread versus right hand thread

In summary, left-handed threads are used in various applications such as pedal and circular saw blade securing, turnbuckles, and fuel gas bottles as a safety measure. They also help differentiate gas lines from other types of lines. However, left-handed threads are not as common in modern cars as they used to be.
  • #1
renjith_p
12
0
Does a left hand thread offer any advantages over a right hand thread?
 
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  • #2
Left pedals on most bicycles have left-hand threads to keep the pedal from unscrewing. Some cars (MGs, e.g.) used to have left-hand lug nuts on the left side, but that's not so common anymore. Some circular saw blades are secured with left-hand nuts for a similar reason.

Turnbuckles obviously have opposite handed threads on either end.

Fuel gas bottles have left hand threads & oxidizer gas bottles have right hand threads as a safety measure for welders. That's why the propane tank on your gas grill is left-handed.
 
  • #3
obafgkmrns said:
Some cars (MGs, e.g.) used to have left-hand lug nuts on the left side, but that's not so common anymore.

When I was a teenager I nearly stripped the lug nut studs on my Mom's '65 Dodge when changing a flat. The nut seem to be getting tighter and a friend watching suggested it might have a left hand thread, which it did.
 
  • #4
They prevent unscrewing in applications where the screw fixes a rotating object, and also help to differentiate gas from hydraulic/liquid/etc lines in cars, burners, etc.
 
  • #5
LJW said:
They prevent unscrewing in applications where the screw fixes a rotating object, and also help to differentiate gas from hydraulic/liquid/etc lines in cars, burners, etc.

Are u saying that gas lines are always fitted with left hand theads?
 

FAQ: Left hand trhread versus right hand thread

What is the difference between left hand thread and right hand thread?

Left hand thread and right hand thread refer to the direction in which the threads on a screw or bolt are cut. Left hand threads are cut in a counterclockwise direction, while right hand threads are cut in a clockwise direction. This means that left hand threads tighten in a counterclockwise direction, while right hand threads tighten in a clockwise direction.

When would you use a left hand thread versus a right hand thread?

The choice between left hand thread and right hand thread depends on the application. Left hand threads are commonly used in situations where the rotation of an object could cause a right hand threaded fastener to loosen, such as in bicycle pedals or rotating machinery. Right hand threads are more commonly used in most applications, including general household use and automotive applications.

Can left hand threaded fasteners be used with right hand threaded fasteners?

It is generally not recommended to use left hand threaded fasteners with right hand threaded fasteners. This is because the direction of rotation needed to tighten or loosen the fasteners is opposite, and using them together can cause confusion and potential damage to the fasteners or the object they are securing.

How do you identify left hand threads and right hand threads?

Left hand threads are typically identified by a marking on the fastener, such as "LH" or a left-facing arrow. Right hand threads are usually not marked, but can be identified by the direction in which they tighten. Additionally, left hand threaded fasteners will have a different thread pitch than right hand threaded fasteners.

Are left hand threaded fasteners more difficult to find and purchase?

In most cases, left hand threaded fasteners can be more difficult to find and purchase compared to right hand threaded fasteners. This is because they are not as commonly used and therefore may not be stocked at all hardware or home improvement stores. However, they can be easily found and purchased online or at specialized stores that cater to specific industries, such as automotive or machinery repair.

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