Gear Box Lab Report: Principles of Input and Output Power

University
Lab Report
by
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Date
 <Your Name> 2018 1 of

Introduction
A gear box is a device that utilizes mechanical advantage to transmit energy in
mechanical form from one device to the other. Gearboxes are most commonly used in
automobiles to provide the necessary torque required to move the vehicle under
different conditions and loads, to shift the vehicle in the required direction and to start
the engine when in neutral condition.
Figure 1:Gearbox Schematic
The gearbox transmits the mechanical energy to other devices in two ways; the first
method is that it increases the output torque when the speed of the shaft is reduced
while the second method is that the input torque is reduced when the output speed of
the shaft is increased [1]. In vehicles for example, the gearbox will provide a high
torque when the vehicle is hill climbing or starting at low speed and on the contrast it
will provide a lower torque when the vehicle is at its highest speed downhill or level
ground.
Gear boxes appear in the market in different shapes and sizes. They are designed to
have a gear ratio that is used to determine the output speed under operation. The gear
ratio is defined as the number of the revolutions that would be made by the output
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shaft if the input shaft made a single revolution [2]. If for example, the gear ratio was
1:4, it would mean that for a single rotation of the input shaft, the output shaft would
make four times as much revolutions.
In this experiment two types of gear boxes for analysis are provided, the right angle
gear box and the in-line gear box as shown in figure one above.
Objectives
The purpose of this lab is to examine and analyse the principles of input and output
power of various arrangements of gear boxes of different types to determine the
efficiency of the gear box at loadings of different magnitude and compare the
efficiency curves of the gear boxes.
Theory
Gear boxes appear in the market with different gear ratios. The gear ratio determines
the output speed for a given input speed. The difference in this speeds is manipulated
to provide the efficiency of the gear boxes. Efficiency of a gear box is defined as the
percentage of the ration of the input power to the output power.
Figure 2: Gearbox Configuration
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Using the diagram above, efficiency can be mathematically expressed as:
Efficincy η= Pout (W )
Pin(W ) X 100 %
Where P is the shaft power in watts. The shaft power is expressed using the equation
below:
P ( Shaft Power )=T ¿
There are two types of powers to the shaft namely; the input power and the output
power. The input power is power that is provided to the input shaft from the electric
motor and is given by the following:
Figure 3: Input Power Measurement
Input Power=T ¿ ( Input shatf torque ) XW ¿ ( input shaft angular Velocity )
The input shaft torque is given by;
T ¿=d ( balance arm length ) xW ( Balnce weight ) .
The output power is the power at the output shaft and is dissipated by the brake belt. It
is determined by the net force that acts on the brake disc. With the aid of the diagram
below, its mathematically expressed as follows:
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