Table of Contents
What is a coast down test?
Coastdown testing is the process of accelerating a vehicle to a high speed on a flat, straight road and coasting in neutral down to a low speed. By recording the amount of time the vehicle takes to slow down, it is possible to obtain a model of the loss- inducing forces affecting the vehicle.
What is road load coefficient?
Collectively, the forces of inertia, friction, and aerodynamic resistance are referred to as “road load,” and the values required to set up a dynamometer to simulate them, called road-load coefficients, are determined outside the laboratory via tests during which the vehicle is driven and then coasted numerous times on …
Why coast down test is done?
The purpose of the coastdown test is to measure the speed profile and distance traveled while the vehicle coasts down from 75 to 5 mph. This testing is to be completed subject to the initial conditions and prerequisites stated in Section 4 of this Test Specification.
WHAT IS A in coast down road load equation?
This three-term equation is expressed as F = A + Bv + Cv2 where F is the road force, v is the vehicle speed. Because it is difficult to measure road-load directly, EPA has adopted the coastdown method to characterize road-load force.
What is Roadload power?
Road load means the specific power absorption setting on a chassis dynamometer equivalent to that experienced by a vehicle of a specific curb weight and engine displacement being driven at a constant speed on a level road.
What is chassis dynamometer testing?
Definition of ‘chassis dynamometer’ The chassis dynamometer measures the mechanical power of the vehicle at the drive-wheels. The test is conducted on a chassis dynamometer that loads the drive wheels to simulate real-world conditions.
How do you measure wheel resistance?
Note 1: Rolling Resistance Coefficient μR is defined by μR = F/G, where F is the force necessary to pull the axle of a tire horizontally in the direction of travel, and G is the vertical load on the tire which is assumed to roll on a flat horizontal surface.
What are different dynamometer tests?
There are several types of dynamometer testing styles used to measure the horsepower and torque of an engine, the thrust of a boat propeller and the dampening characteristics of a shock absorber. Chassis dynamometers are able to identify the power reaching the drive tires.
How is rolling torque calculated?
The torque is obtained by integrating the frictional force multiplied by roll radius over the arc of contact (lagging and leading zones). The negative sign before the second term is due to the fact that in leading zone the metal moves faster than the rolls hence it helps to rotate the rolls.
How do you calculate rolling resistance?
What is the value of rolling resistance?
The coefficient of rolling resistance for a pneumatic tire used in motor vehicles on a smooth asphalt or concrete surface is indicated in the range 0.007 to 0.02 [1-9], most often indicated around 0.012.
What is the unit of rolling resistance?
Rolling resistance coefficient and is force per unit mass, where g is the acceleration of gravity in SI units (meters per second square).
What is a dynamometer test?
Troubleshoot, Identify, Verify. An engine dynamometer is a device used to test an engine that has been removed from a vehicle, ship, generator, or any other piece of equipment powered by an internal combustion engine. The purpose is to confirm performance before the engine is installed back in the equipment.
INTRODUCTION Coast down is one of the most frequent tests for motor vehicles and consists in vehicle launch from a certain speed with the engine ungeared, simultaneously recording the speed and travelled distance until vehicle stops.
What is co-coast-down Experimental Test in the Automotive Research?
coast-down experimental test in the automotive research. That test consists in launching of a motor vehicle from a certain speed with the engine disengaged and ascertaining of the current speed and distance covered during the free rolling, till vehicle stops. First it is indicated a modality to determine by computation the vehicle kinematics.
What is the co-coastdown programme?
Coastdown Programme. This programmme calculates the coefficient of drag and coefficient of rolling resistance using data gathered from coastdown testing. This data is very useful for the calculation of vehicle performance parameters such as acceleration, top speed etc.
What are the main factors affecting the accuracy of coast-down tests?
Th e acquisition errors and the change of wind speed and road slop are the main items affecting the coast-down test accuracy. [1] *** STAS 6926/9-70 Autovehicule. Metode de încercare. I ncercarea la rulare libera. (Romanian Standard: Motor vehicles. Testing methods. C oasting test.) [3] Preda,I. Untaru.M. Peres,Gh. Ciolan,Gh.