KENYA COMPUTER TECHNICIANS: ALL ABOUT SPEED GOVERNORS

Kenya legal requirements

According to the law, speed limits in Kenya depend on type of settlement, road and vehicle. In trading centers, towns, municipalities and cities, the limit is 50km/h, elsewhere; it is 80km/h on single carriageway highways and 110km/h on dual carriageways. The limit is 30km/h near schools.

What is a Speed Governor/Speed Limiter.

A speed limiter is a governor used to limit the top speed of a vehicle. For some classes of vehicles and in some jurisdictions they are a statutory requirement, for some other vehicles the manufacturer provides a non-statutory system which may be fixed or programmable by the driver.

Vehicle Speed limiter or Speed governor is a device used to restrict the top speed of the vehicle for security reasons, widely used in public service vehicles (buses, school buses) and heavy goods vehicles. Normally speaking, the vehicle is already equipped with an onboard speed limit system prevent the vehicle exceeding certain speed.

However in reality usage, the traffic might get dangerous with the pre-controlled speed, especially for school buses, public buses, and heavy construction trucks. Then external speed limiter (speed governor) is needed to ensure the public security.

The throttle is a mechanism used to control the inlet gases so as to increase or decrease vehicle speed. Typically, the throttle is a butterfly value placed on the entrance of the intake manifold in a fuel-injected engine or in the carburetor in a carbureted engine. Usually the throttle valve is connected and controlled with a throttle pedal in vehicles.

Types of Governors

The type of governor used on diesel engines is dependent upon the application required. The six basic types of governors are as follows:

1. Mechanical centrifugal flyweight style that relies on a set of rotating flyweights and a control spring; used since the inception of the diesel engine to control its speed.

2. Power-assisted servo mechanical style that operates similar to the mechanical centrifugal flyweight but uses engine oil under pressure to move the operating linkage.

3. Hydraulic governor that relies on the movement of a pilot valve plunger to control pressurized oil flow to a power piston, which, in turn, moves the fuel control mechanism.

4. Pneumatic governor that is responsive to the air flow (vacuum) in the intake manifold of an engine. A diaphragm within the governor housing is connected to the fuel control linkage that changes its setting with increases or decreases in the vacuum.

5. Electromechanical governor uses a magnetic speed pickup sensor on an engine-driven component to monitor the rpm of the engine. The sensor sends a voltage signal to an electronic control unit that controls the current flow to a mechanical actuator connected to the fuel linkage.

6. Electronic governor uses magnetic speed sensor to monitor the rpm of the engine. The sensor continuously feeds information back to the ECM (electronic control module). The ECM then computes all the information sent from all other engine sensors, such as the throttle position sensor, turbocharger-boost sensor, engine oil pressure and temperature sensor, engine coolant sensor, and fuel temperature to limit engine speed.