A keyed shaft has a small recess where a key is placed in. We are probably all familiar with keyed shafts because this type is predominant in the industry. Shafts come in two varieties: Keyed and splined. However, there are three options to get great alignment with a pump or motor.

This is not ideal and will definitely wear out the spider coupler faster. Each loading of the jib changes the alignment if only for a few seconds.

Even if we get all of these things perfectly aligned, which didn’t happen, if the jib is loaded to this side, the stiffness of the frame causes these to shift.Washers were used to shim and they have discrete shimming heights which limits adjustment. The aligning of the shafts is entirely done by positioning the engine.As temperature and humidity change, so will the height and angle of the engine. The motor is mounted on a piece of wood.The pump (left) is mounted on a thin piece of flat steel and cannot be adjusted for angularity.The example here, a log splitter, is almost exactly how not to do this. It can mean the difference between a long-lasting system and one that constantly needs maintenance. Keeping your pump and motors on the same center and parallel is critical and often difficult to do. The sizes are already designed to be able to properly carry the load with medium strength fastener (Grade 5 or equivalent) The Society of Automotive Engineers (SAE) has standardized the mounting flanges for hydraulic pumps and motors using a letter codes and the number of bolts used. Plus, manufacturers can often bring a product to market quicker since there aren’t many custom options. The fewer the choices, the easier it is on engineers. The standard takes a seemingly infinite number of combinations and boils it down to a manageable number of combinations. SAE led the way with standardized shafts and mounting flanges in SAE J744. There was a standardization that took place years ago. Why aren’t there more? Also, what about the outside of the parts? They look like they were designed to be mated with something.

With the use of these couplers, we can adapt and fit many different types of shafts together, but interestingly, there are so few choices! Granted, there are lots of choices in the catalogue, but it seems that there should be many more shaft sizes, spline cuts and keys to choose from. Jaw-style couplers help with joining shafts together. It is not uncommon that we will need to couple pumps, motors and/or engines together.

Sae 6b spline shaft dimensions