Friction Bearing U-Joints compared to Twin Spring Coupling

Friction bearing U-joints replacement

Friction bearing U-joints verses Twin Springs no maintenance power transmission couplings.

In the world of universal joints there are only two versions, the old block and pin and the newer needle bearing u joints.

Friction bearing u-joints was originally patented in 1904 making it over a century old, and the technology inside it hasnt changed, the introduction of needle bearings gave the manufacturer of uni joints a new option for customers who wanted a uni joint that could run faster and at improved angles of misalignment.

Friction bearings u-joints are cheap, made from steel and used in lots of industries but are slow and need maintaining constantly.

Sadly the design of a universal joint means that both uni joint types require maintenance both greasing to ensure they last longer and in the case of the needle bearing uni joint, new bearings.

So how does block and pin U-joints work, it is exactly as it sounds a rounded metal cube (block) with 4 pins attaching it to the input and output hubs of the uni joint. Simple design but it has its uses but also its drawbacks.

The U-joint requires a pivot point to work, whether it be block and pin or needle bearing, the pins in the block allow that pivot to happen, all the way up to 25° but only at 1750 RPM, this means that it is unusable for anything at a higher speed, why?

There are two reasons, 1. Vibration and 2. Created heat

  1. Vibration – The more two shafts become out of alignment means they become more out of “phase”, the being out of phase means the coupling, accelerates and deccelerates which means the pulsing creates vibration, the higher the angle of misalignment the higher the vibration.
  2. Created heat – The misalignment and speed means the pins inside the block heat up as the friction from their use increases, and the force (torque) applied increases as well.The only way to avoid this is through a constant application of grease to reduce the friction and absorb the heat rather than the heat being transferred into the block and making the holes the pins are inserted into shrink due to the expansion of the block.

The friction bearing U-joints are able to transfer lots of torque and work at a typical angle of 8° or less, which is great for most applications but the constant greasing to keep the coupling functioning detracts from its use. Machinery has to stopped, protection/grease boots removed and more grease applied, reassembly and the machinery can get back to work.

If this is a bi monthly task it certainly bites into the amount of working time that the machinery can be used per month.

Friction bearing U-joints vs Twin Spring Coupling- How are they different

Twin Spring offers something different in a number of ways

We combine the high torque of a u joint and more flexibility than either  block and pin u-joints and needle bearing u-joints

Add to that high speed, so where you couldn’t use block and pin u joints you now can with Twin Spring Couplings.

No block and no needle bearings, no we dont use either, the twin spring design means our coupling pivots on a central ball bearing which only needs to be greased semi annually or annually.

Our coupling is a one piece design so no need for replacement parts bearings, blocks and no broken input or output yokes.

Installed shear pins mean the Twin Spring Coupling can shear the installed safety pins rather than damaging equipment, new shear pins can be pressed into the hubs and back to business.

As for construction, the Twin Spring Coupling are made of a steel alloy, making them longer lasting compared to block and pin u joints plain steel construction.

Its time for something new, a longer lasting less maintenance high speed power transmission friction bearing u joints replacement

For more information on our range go to for more information on our range of flexible no maintenance coupling





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