Friction-Instability: A New Design Parameter for Brakes

1971 ◽  
Vol 93 (4) ◽  
pp. 1225-1228 ◽  
Author(s):  
W. L. Starkey ◽  
T. G. Foster ◽  
S. M. Marco
Keyword(s):  
Quality Control ◽  
Coefficient Of Friction ◽  
Design Parameter ◽  
Control Device ◽  
Experimental Facility ◽  
Test Results ◽  
Effective Manner ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
The Right

A new design parameter, friction-instability, is defined in this paper. Friction-instability is a variation in the coefficient of friction which may occur at any time during the life of a brake lining. A friction-index is defined which measures this variation. A lining which has a high friction index may tend to cause an automobile to swerve either to the right or to the left. A unique experimental facility is described by means of which the friction-instability characteristics of brake linings can be measured. Test results using this facility are presented and interpreted. The friction-index is proposed as a new parameter which should be taken into consideration when brakes are designed and, developed. This index should be particularly useful as a quality control device to insure that machines which use mass-produced braking systems will perform in a safe and effective manner.

Calculation of Cylindrical Worm Gear Drives of Different Tooth Profiles

1981 ◽  
Vol 103 (1) ◽  
pp. 73-82 ◽  
Author(s):  
H. Winter ◽  
H. Wilkesmann
Keyword(s):  
Coefficient Of Friction ◽  
Theoretical Basis ◽  
Power Loss ◽  
Influence Factor ◽  
Load Capacity ◽  
Worm Gear ◽  
Important Influence ◽  
Test Results ◽  
The Coefficient Of Friction ◽  
Gear Drives

The formulae of classical hydrodynamics are not suitable for the calculation of load capacity and power loss of worm gear drives. Thus a theoretical basis had to be developed for the comparison of different tooth profiles, materials of worm and worm wheel and lubricants. The data obtained were compared with test results. It proved that the coefficient of friction is an important influence factor.

Frictional Vibrations

1955 ◽  
Vol 22 (2) ◽  
pp. 207-214
Author(s):  
David Sinclair
Keyword(s):  
Coefficient Of Friction ◽  
Equations Of Motion ◽  
Static Friction ◽  
Uniform Motion ◽  
Friction Characteristic ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
Solid Bodies ◽  
Frictional Vibrations

Abstract Frictional vibrations, such as stick-slip motion and automobile-brake squeal, which occur when two solid bodies are rubbed together, are analyzed mathematically and observed experimentally. The conditions studied are slow uniform motion and relatively rapid simple harmonic motion of brake lining over a cast-iron base. The equations of motion show and the observations confirm that frictional vibrations are caused primarily by an inverse variation of coefficient of friction with sliding velocity, but their form and occurrence are greatly dependent upon the dynamical constants of the mechanical system. With a constant coefficient of friction, the vibration initiated whenever sliding begins is rapidly damped out, not by the friction but by the “natural” damping of all mechanical systems. The coefficient of friction of most brake linings and other organic materials was essentially invariant with velocity, except that the static coefficient was usually greater than the sliding coefficient. Most such materials usually showed a small decrease in coefficient with increasing temperature. The persistent vibrations resulting from the excess static friction were reduced or eliminated by treating the rubbing surfaces with polar organic compounds which produced a rising friction characteristic.

Theoretical and experimental investigation of non-asbestos friction lining material applied in automotive drum brake

2019 ◽  
Vol 234 (6) ◽  
pp. 972-985
Author(s):  
Dinesh Subhash Shinde ◽  
KN Mistry ◽  
Mukesh Bulsara
Keyword(s):  
Coefficient Of Friction ◽  
Test Procedure ◽  
Frictional Resistance ◽  
Theoretical Models ◽  
Surface Phenomenon ◽  
Vehicle Speed ◽  
Lining Material ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
Friction Lining

Automotive brakes are the important machine element which provides an artificial frictional resistance to control the speed of an automobile. In the present work, theoretical models for the coefficient of friction between brake drum and friction liner are generated and simulated using MATLAB Simulink. A test set up designed and manufactured according to the brake lining quality test procedure (SAE J661) is used to investigate tribological properties of a non-asbestos friction lining material having 11 different constituents, which is manufactured from one of the brake liner manufacturer. An experiment is designed using response surface methodology (RSM) with vehicle speed, braking force, and sliding distance as the input parameters, whereas coefficient of friction and wear as an output. It is found that vehicle speed is the most significant parameter among the three. Fade and recovery behavior of the friction lining material is also studied and it is found that the developed friction lining material satisfies the criteria specified in SAE J661. Scanning electron microscope (SEM) and energy dispersive spectoscopy (EDS) have revealed the significant surface phenomenon.

The Data Processing Technique of Metallic Sheet Friction Coefficient Determination

2012 ◽  
Vol 184-185 ◽  
pp. 688-691
Author(s):  
Huan Xue ◽  
Rong Feng Li ◽  
Hong Chuan Zhu
Keyword(s):  
Data Processing ◽  
Coefficient Of Friction ◽  
Normal Pressure ◽  
Processing Technique ◽  
Test Results ◽  
Friction Zone ◽  
Data Processing Method ◽  
The Coefficient Of Friction ◽  
Processing Techniques ◽  
Metallic Sheet

The definition and research background of friction is introduced. The reason of generation of friction is analyzed, the importance of the coefficient of friction test in sheet metal forming field is indicated. The testing principle of coefficient of friction on metallic sheet is presented. The basic data processing method of the test is described. Two important data processing techniques which will obviously effects the test results, including effective friction zone and normal pressure have been carefully studied. The comparison result shows these techniques can effectively enhance the testing stability and precision.

Comparison of Dry-Film and Zinc-Phosphate Lubricant for Tube Cold Forming

2011 ◽  
Vol 295-297 ◽  
pp. 2362-2365
Author(s):  
Zhi Yan Cheng
Keyword(s):  
Coefficient Of Friction ◽  
Zinc Phosphate ◽  
Test Results ◽  
Tube Surface ◽  
Cold Forming ◽  
Breakdown Time ◽  
Significant Difference ◽  
Potential Applications ◽  
The Coefficient Of Friction ◽  
Dry Film

Dry-film and zinc-phosphate (Zn-P) lubricants were compared for potential applications of dry-film lubricant in tube cold forming processes through the twist compression test. Test results showed that the coefficient of friction (m) had no significant difference between Zn-P soap lube and dry-film lube. The lube coating breakdown time is different between Zn-P soap and dry-film lube. A preliminary industrial trial with dry-film coated tube through the cold drawn over a mandrel showed that the tube surface quality is good and comparable with the Zn-P coated tubes.

scholarly journals Test on a brake lining damper for structures

1985 ◽  
Vol 18 (3) ◽  
pp. 280-284 ◽  
Author(s):  
R. G. Tyler
Keyword(s):  
Friction Force ◽  
Coefficient Of Friction ◽  
Relative Motion ◽  
Steel Plate ◽  
Hysteresis Loops ◽  
Continuous Movement ◽  
The Coefficient Of Friction ◽  
Brake Lining

Tests were carried out on a brake lining damper intended to dissipate energy between parts of a structure having relative motion during earthquake attack. The device operates by the sliding of a steel plate clamped against a brake lining. Hysteresis loops for the damper showed peaks for the breakaway friction force, when the value of the force was up to twice that obtained for continuous movement. Also values of the coefficient of friction derived from the test were lower than those quoted elsewhere. Further testing is required prior to the use of the method in structures.

TRIBOLOGICAL CHARACTERISTICS OF POLYURETHANES USED FOR THE SOLES OF FOOTWEAR

Tribologia ◽  
2021 ◽  
Vol 294 (6) ◽  
pp. 71-75
Author(s):  
Jacek Przepiórka ◽  
Marian Szczerek ◽  
Marian W. Sułek
Keyword(s):  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Base Material ◽  
Operating Conditions ◽  
Test Results ◽  
Footwear Industry ◽  
Wear And Tear ◽  
Variable Friction ◽  
The Coefficient Of Friction ◽  
Shoe Soles

The inability to take into account the type of base material (floor, pavement, soil), as well as the inability to take into account the variable friction conditions – load, intermediary medium (water, loose abrasive, sand or other soil particles), sliding velocity, and ambient temperature – is a significant limitation the use of friction methods and devices used so far in the footwear industry to precisely anticipate the behavior of the bottom materials in the actual operating conditions of the footwear. These limitations prompted the authors to adapt a tribological tester for this purpose, used in the area of construction and operation of machines and material engineering. A research methodology was developed and, in order to verify it, measurements of the coefficient of friction and wear of polyurethane used for shoe soles in combination with a raw and varnished wooden substrate were carried out. The obtained test results are characterized by diversity, which proves the high research resolution of the developed method. It allows determining the coefficient of friction of associations influencing the slip of the footwear and the wear and tear that determines the length of use of the footwear.

Development of Portable Tester for Measuring Skid Resistance and Its Speed Dependency on Pavement Surfaces

1996 ◽  
Vol 1536 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Kazuo Saito ◽  
Takashi Horiguchi ◽  
Atsushi Kasahara ◽  
Hironari Abe ◽  
John Jewett Henry
Keyword(s):  
Coefficient Of Friction ◽  
International Association ◽  
Constant Load ◽  
Skid Resistance ◽  
Test Results ◽  
Maintenance Program ◽  
Service Period ◽  
Friction Component ◽  
The Coefficient Of Friction

Skid resistance is an important factor in a rational maintenance program for pavement surfaces. Therefore, the skid resistance of a road surface is monitored by maintaining skid resistance inventories; in addition, spot checks are made at high accident sites. The equipment, called the dynamic friction tester (DF tester), is a disc-rotating-type tester that measures the friction force between the surface and three rubber pads attached to the disc. The disc rotates horizontally at a linear speed of about 80 to 20 km/hr under a constant load, so the DF tester can measure the skid resistance at any speed in this range with a single measurement. At the same time, the results provide speed dependency of skid resistance that will be as close as possible to the results obtained by other testing modes. The DF tester can measure on flat as well as rutted surfaces, the depths of which are less than 6 mm. In that case, the coefficient of variation is found to be less than 10 percent. The long-term characteristics of the coefficient of friction were measured by the DF tester, the British pendulum tester and the mini-texture meter. The coefficient of friction increases moderately with the traffic service period (up to 35 weeks) and decreases with increasing speed. The test results showed a significant speed dependency on the coefficient of friction measured by the DF tester although there was a high relationship between the coefficient of friction of the DF tester and the British pendulum number at each point and at each measuring speed. A weak relationship was found between the coefficient of friction and the sensor-measured texture depth values produced by the texture meter. Results of the Permanent International Association of Road Congresses experiment to compare and harmonize texture and skid resistance measurements indicate that the DF tester is capable of reporting the friction component (F60) of the international friction index using the friction coefficient at 60 km/hr.

Analysis of the inertial propulsion concept

2020 ◽  
pp. 12-19
Author(s):  
A. A. Sabirzyanov ◽  
Keyword(s):  
Remote Control ◽  
Friction Force ◽  
Coefficient Of Friction ◽  
Average Velocity ◽  
Classical Mechanics ◽  
Average Speed ◽  
The Coefficient Of Friction ◽  
The Difference ◽  
The Right ◽  
Propulsion Concept

In this paper, an inertial device of the simplest design is proposed, which allows us to visually analyze the principle of its operation. The device is a radio-controlled car placed on the bottom of a long light cardboard box. The box is on the table. Using the remote control, the car accelerates and collides with one of the walls. On impact, the box moves across the table. Next, the car is taken to the opposite wall by the remote control without a collision. Then the process is repeated, as a result of which the device jerks along the table in one direction (in the example - to the right). The advantage of this method of control is that it is contactless, the disadvantage is that it is manual. In the framework of classical mechanics, the average speed of the box movement on the table is calculated. It depends on the ratio of the mass of the car and the box, the proportion of weight that falls on the driving wheels, the coefficient of friction between the wheels and the bottom of the box, the coefficient of friction between the box and the table, the difference in the length of the box and the car. It is shown that the average speed with a decrease in the friction force on the side of the support should first increase, and with a further decrease in friction - decrease. A condition is found under which the dependence of the average velocity on the friction force has a maximum.

scholarly journals The tribological properties of lubricating greases produced on vegetable base and modified of polytetrafluoroethylene

2020 ◽  
Vol 37 (1−2) ◽  
Author(s):  
Rafal Kozdrach
Keyword(s):  
Correlation Function ◽  
Fatigue Life ◽  
Rheological Properties ◽  
Coefficient Of Friction ◽  
Sunflower Oil ◽  
Test Results ◽  
Wear Protection ◽  
The Coefficient Of Friction ◽  
Load Conditions ◽  
Modifying Additive

The article presents the results of research on the influence of polytetrafluoroethylene additive on the tribological and rheological properties of selected lubricant compositions. Based on the obtained test results, it was found that the introduction of a modifying additive to the lubricant structure allows a significant reduction of the coefficient of friction, thus increasing the efficiency of tribological protection of the tribosystem. All lubricating compositions modified with at least 1% polytetrafluoroethylene guarantee effective anti-wear protection under load conditions of the tribosystem. Modification of the tested lubricating compositions with the applied additive affects the increase of indicators characterizing the fatigue life of the examined lubricating greases based on sunflower oil. The introduction of the polytetrafluoroethylene into the structure of the tested lubricants changed the values of the MSD correlation function and the G’ and G’’ modules, which significantly influenced the internal structure of the tested lubricant compositions.

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