Differences between Gear Pumps and Piston Pumps

Blog | August 20th, 2017

Fluid power is generated when a piston rises and falls or a gearing assembly spins. To put it another way, there are two dominant pump types employed as hydraulic positive displacement pumps in fluid-based apparatus. The first, gear pump technology, is different from the piston pump principles we’re about to review in the next paragraph.

Hydraulic Drive Principles: Reviewing Piston Pumps 

Based on an axial architecture, this mechanism uses a cylindrical form factor. A sealed plunger rises in the cylinder, then it generates inlet suction. It concludes this cycle by driving the vacuum-transferred fluid to the pump outlet port. Pressure isn’t a result of this axial motion, but fluid transference most definitely does take place. However, there’s a pulsing effect that accompanies the fluid transportation mechanism, just like the pulse that’s produced by a human heart valve.

Gear Pump Fundamentals: Studying Meshing Teeth 

Although this device transports hydraulic fluid, just as the piston pump does, the internal workings of this piece of pumping equipment are wholly different. In terms of its operating principles, the reciprocating mechanism is replaced by two gears. There are specially shaped teeth fitted to the rim of both spinning wheels. As they spin, pockets of fluid are carried by the gaps in the gear teeth. Still classed as a positive displacement device, the architecture inside a gear pump is seen to be significantly different when it’s compared with an axially configured piston pump. Granted, they both carry out similar duties, but surely those mechanical dissimilarities are going to create a few performance-based differences, too.

Gear Pumps vs. Piston Pumps: A Hydraulic Showdown 

Reciprocating pumps are relatively complex mechanical components in what should be a straightforward fluid circuit. It’s because of the rods and pistons, seals and abrasive surfaces, that this mechanism requires greater maintenance. Additionally, the piston pump, a central member of the reciprocating family, is a pulse-heavy device. The vacuum action and piston retraction distances create intermittent flow, although that pulsing effect is barely discernible. Gear pumps minimise this effect, except when the number of teeth on the gearing wheels generate a similar but much-attenuated pulse.

In terms of inner geometry, there are major differences between gear pumps and piston pumps. As long as that reciprocating assembly is axially aligned and lubricated, the sealed plungers will work quietly and powerfully, albeit it with a signature pulsing effect. Hydraulic gear pumps, in the meantime, use their rotating wheels to spin fluid-transporting teeth segments and to radially carry those tiny fluid packets at a near pulse-free rate to the outlet side of the pump, where the fluid drives its actuators without producing an intermittent force attenuation effect.

Mobile Hydraulic Specialties Pty Ltd

Factory 89, 38-40 Popes Road
Keysborough, Victoria, 3173

Phone: (03) 9798-6511

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