Common Governor Types on Small Engines

Small engines, ubiquitous in our daily lives, power a myriad of tools and equipment, from lawnmowers to generators. At the heart of these engines lies the governor, a critical component responsible for regulating the engine's speed. Understanding the common governor types on small engines is essential for maintenance, troubleshooting, and even selecting the right engine for a specific application.

How To Adjust Mechanical Governor On Small Engines
How To Adjust Mechanical Governor On Small Engines

Governors play a pivotal role in ensuring the engine's longevity and performance. They work by adjusting the fuel supply or ignition timing in response to changes in engine load. This article delves into the common governor types found in small engines, their working principles, and applications.

various types of engine parts for cars and trucks
various types of engine parts for cars and trucks

Mechanical Governors

Mechanical governors are the most common type found in small engines. They use a simple yet effective mechanism to control engine speed. These governors consist of a spring-loaded lever arm connected to the engine's throttle valve.

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Submarine Main Propulsion Diesels - Chapter 10

Here are two key sub-types of mechanical governors:

Centrifugal Governors

the diagram shows how diesel engine works and what it is doing to work on them
the diagram shows how diesel engine works and what it is doing to work on them

Centrifugal governors use the centrifugal force generated by the rotating engine shaft to control the engine's speed. As the engine speed increases, the governor's weights or flyweights move outward due to centrifugal force, closing the throttle valve and reducing fuel supply. Conversely, when the engine speed decreases, the weights move inward, opening the throttle valve and increasing fuel supply.

Centrifugal governors are simple, reliable, and widely used in small engines like lawnmowers, chainsaws, and outboard motors. They are particularly suitable for constant-speed applications where precise speed control is not critical.

Inertia Governors

How Small Engine Ignition System Works
How Small Engine Ignition System Works

Inertia governors, also known as dead-weight governors, use the inertia of a heavy mass to control engine speed. They consist of a heavy weight or flywheel connected to the throttle valve via a lever arm. As the engine speed increases, the inertia of the weight resists the increase, closing the throttle valve and limiting the engine's maximum speed.

Inertia governors are typically used in engines that require a higher degree of speed control, such as those in power tools and some small generators. They are less sensitive to changes in engine load compared to centrifugal governors but offer better speed stability at high loads.

Electronic Governors

an image of a carburet diagram with parts labeled in the text below it
an image of a carburet diagram with parts labeled in the text below it

Electronic governors, also known as electronic control units (ECUs), have become increasingly common in modern small engines. They use sensors, microcontrollers, and actuators to precisely control engine speed. Electronic governors offer several advantages over mechanical governors, including better fuel efficiency, lower emissions, and improved speed control.

Here are two sub-types of electronic governors:

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an image of various gears and gear for different types of vehicles, including the engine
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an electrical diagram showing the workings and parts for a car's alter, which is also
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an image of carburets and parts labeled
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Inderjit - #technology #electronics | Facebook

Speed-Density Governors

Speed-density governors use a mass airflow (MAF) sensor to measure the amount of air entering the engine. The ECU then calculates the engine's speed and load based on this airflow and adjusts the fuel supply accordingly. This type of governor is highly responsive and can provide precise speed control, making it ideal for applications that require variable speed, such as in some lawnmowers and snowblowers.

Speed-density governors are also used in engines with electronic fuel injection (EFI) systems, where the MAF sensor provides real-time feedback to the ECU, allowing for precise fuel metering and optimal engine performance.

Throttle Position Sensors (TPS) Governors

Throttle position sensors (TPS) governors use a potentiometer or a hall-effect sensor to measure the position of the engine's throttle valve. The ECU uses this information, along with data from other sensors like the crankshaft position sensor (CPS) and the engine's rev limiter, to control engine speed.

TPS governors are commonly used in engines with a cable-operated throttle, such as in some outboard motors and handheld power equipment. They provide a simple and cost-effective means of engine speed control, although they may not offer the same level of precision as speed-density governors.

Understanding the different governor types and their applications is essential for small engine owners, operators, and maintenance technicians. Whether you're troubleshooting a lawnmower, selecting the right engine for a specific application, or simply curious about how these engines work, familiarity with common governor types can help you make informed decisions and ensure optimal performance from your small engine.