Changing the direction of rotation in a hydraulic gear pump 

The center cutouts on the center section are slightly different sizes, bigger on the low pressure side to ensure good supply of oil, and the plates that fit up to the ends of the gears have those odd shaped seals under them. The end plates on many brands, such as muncie and commercial have the oil passages in them, the turolla has them in the casting. The oil passages allow high pressure oil to get behind the plates and to hold them tight to the gears to help them seal. If the plates are backwards there is no oil pressure behind them, and they won't seal.

@@DillonHFM Ok, so what you are saying is the back side of the wear plates need to be ported to the pressure side to work. If ported to the suck side, they don't energize. Correct ?

Correct, they need pressure rather than suction

The pump rotation has to do with the way that it is mounted. Depending on the gearbox or motor that is powering the pump, the input shaft of the pump might have to spin clockwise or counterclockwise. For example on the Allison transmission in my skidder, there are two different PTO mounting locations, one spins clockwise, and the other spins counter-clockwise. If a pump is spun the wrong way, it will not work properly

@@DillonHFM sounds like I might have it installed incorrectly on my international 4700??!! Because it’s pulling from the suction side…

The hydraulic oil is a lubricant and coats everything on its way through. Oil has a film characteristic and forms a protective film that lubricates mating surfaces, this is how all lubricating oils work, and is why it is important to have good oil, water and other contaminants don't do this and cause damage. As for the heat, the flow of cool oil keeps the pump cool, which is why dead heading a hydraulic system can kill a pump pretty quickly. Once the flow isn't there, the heat builds quickly. This is also why the rule of thumb is 1 gallon of oil capacity per gpm of the pump

How can you tell if the pump is reversible