Mechanical Engineering

Slider Crank Inversions

The slider crank is a very common linkage that is found in a variety of machines.  The most recognizable version of the slider crank is found in an engine in the form of a crank shaft, connecting rod, piston, and cylinder.  This mechanism also comes in different forms called slider crank inversions. The slider crank …

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Hydraulic Pump Calculations

Hydraulic pumps are the heart of a hydraulic system.  In this article we’ll present the equations for hydraulic pump calculations and explore efficiencies. We’ll start with the equations in SI and US units. Pump Equations – SI Pump Equations – US Hydraulic Pump Efficiencies There are three types of efficiency associated with a hydraulic pump. …

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Hydraulic Motor Calculations

In this article we’ll dive into hydraulic motor calculations and the important topic of efficiency.  Many hydraulic calculators ignore efficiency altogether and merely calculate theoretical values with 100% efficiency.  Manufacturers typically don’t get too deep into efficiency either. First we’ll present the equations for various parameters of a hydraulic motor in both SI and US …

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Planetary Gear Train Analysis

The planetary gear train is an important, but complex mechanism.  When it comes to analyzing rotation directions and gear speeds, intuition is not enough.  We’ll look at the superposition method to determine speeds and rotation directions. For a planetary (a.k.a. epicyclic) gear train there are three possible inputs/outputs: two gears and the planetary gear carrier.  …

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Helical Gear Forces

In this article we’ll look at helical gear forces that result from gear mesh. These forces are important to determine the loads on shafts and bearings.  Unlike spur gears, single helical gears generate an axial force.  This thrust can be canceled by using a double helical gear (herringbone). This article focuses on single helical gears. …

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Spur Gear Forces

In this article we’ll look at spur gear forces that result from gear mesh.  These forces are important to determine the loads on shafts and bearings. Gear Mesh When two spur gears mesh, their pitch circles touch as shown below. Looking at the free body diagrams for each gear, there is a normal force acting …

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Worm Gear Forces

Calculating worm gear forces is necessary to determine bearing reactions and shaft loads.  Because of the sliding action between the worm and gear, friction plays a major role in a worm gear set’s efficiency. For this discussion, we assume the worm and gear shafts are 90 degrees apart and that the worm is driving the …

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