Some Effects of Lubricant Composition and Tappet Rotation on Cam/Tappet Friction

1989 ◽  
Vol 111 (4) ◽  
pp. 683-691 ◽  
Author(s):  
P. A. Willermet ◽  
J. Pieprzak
Keyword(s):  
Experimental Data ◽  
Frictional Contact ◽  
Angular Resolution ◽  
Friction Model ◽  
Journal Bearings ◽  
Valve Train ◽  
Wave Form ◽  
Rolling Element Bearings ◽  
Lubricant Composition ◽  
Rolling Element

A cam/tappet friction rig was constructed from a 1.6 L Ford valve train. The head casting and the camshaft were shortened so that only two journal bearings remained. Only one of the two remaining cam/tappet contacts was used as a frictional contact. All other contacts were equipped with rolling element bearings so that essentially all the turning torque came from cam/tappet friction and valve spring forces. The rig, together with a data acquisition/wave form analyzer system and a computer, was capable of measuring instantaneous torque with an angular resolution of less than one degree, and reducing the data to provide calculated values for parameters such as the friction coefficient. The experimental data were compared with results from a cam/tappet friction model to assist in interpretation. The data and model illustrated that lubricant composition and tappet rotation have important effects not only on overall friction, but also on the shape of friction versus cam angle curves.

Simultaneous Monitoring of Rolling-Element and Journal Bearings Using Analysis of Structure-Born Ultrasound Acoustic Emissions

2010 ◽  
Author(s):  
A. Albers ◽  
M. Dickerhof
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emissions ◽  
Piezoelectric Sensor ◽  
Journal Bearings ◽  
Rolling Element Bearings ◽  
Acoustic Emission Sensor ◽  
Outer Race ◽  
Rolling Element ◽  
Characteristic Values ◽  
Acoustic Emission Technology

The application of Acoustic Emission technology for monitoring rolling element or hydrodynamic plain bearings has been addressed by several authors in former times. Most of these investigations took place under idealized conditions, to allow the concentration on one single source of emission, typically recorded by means of a piezoelectric sensor. This can be achieved by either eliminating other sources in advance or taking measures to shield them out (e. g. by placing the acoustic emission sensor very close to the source of interest), so that in consequence only one source of structure-born sound is present in the signal. With a practical orientation this is often not possible. In point of fact, a multitude of potential sources of emission can be worth considering, unfortunately superimposing one another. The investigations reported in this paper are therefore focused on the simultaneous monitoring of both bearing types mentioned above. Only one piezoelectric acoustic emission sensor is utilized, which is placed rather far away from the monitored bearings. By derivation of characteristic values from the sensor signal, different simulated defects can be detected reliably: seeded defects in the inner and outer race of rolling element bearings as well as the occurrence of mixed friction in the sliding surface bearing due to interrupted lubricant inflow.

Simulations and Measurements of the Vibroacoustic Effects of Replacing Rolling Element Bearings With Journal Bearings in a Simple Gearbox

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Stephen A. Hambric ◽  
Micah R. Shepherd ◽  
Robert L. Campbell ◽  
Amanda D. Hanford
Keyword(s):  
Finite Element Analysis ◽  
Journal Bearings ◽  
Component Mode Synthesis ◽  
Rolling Element Bearings ◽  
Element Analysis ◽  
Free Boundary Conditions ◽  
Damping Coefficients ◽  
Rolling Element ◽  
Gearbox Vibration ◽  
Solution Methods

The effects of replacing rolling element bearings with journal bearings on the noise and vibration of a simple gearbox are computationally and experimentally evaluated. A modified component mode synthesis (CMS) approach is used, where the component modes of the shafting and gearbox housing are modeled using finite element analysis (FEA). Instead of using component modes with free boundary conditions, which is typical of CMS, the shafting and gearbox are coupled using nominal impedances computed for the different bearing types, improving convergence of the solution. Methods for computing the actual bearing impedances, including the high damping coefficients in journal bearings, are summarized. The sound radiated by the gearbox is computed using a boundary element (BE) model. The modeling results are validated against measurements made at the NASA Glenn Research Center. Both simulations and measurements reveal that the journal bearings, although highly damped, do not necessarily lead to strong reductions in gearbox vibration and noise.

Dynamics of Rolling Element—Bearings Experimental Validation of the DREB and RAPIDREB Computer Programs

1985 ◽  
Vol 107 (1) ◽  
pp. 132-137 ◽  
Author(s):  
P. K. Gupta ◽  
J. F. Dill ◽  
H. E. Bandow
Keyword(s):  
Experimental Data ◽  
Experimental Validation ◽  
Ball Bearing ◽  
Rolling Element Bearings ◽  
Mass Center ◽  
Angular Contact Ball Bearing ◽  
High Speeds ◽  
Rolling Element ◽  
General Motion ◽  
Good Agreement

The general motion of the cage predicted by the computer models in an angular contact ball bearing operating up to two million DN is compared against experimental data. Both the computer predictions and experimental data indicate a certain critical shaft speed at which the cage mass center begins to whirl. The predicted and measured whirl velocities and orbit shapes are in good agreement. The axial and radial velocities of the cage mass center also agree within the tolerance band of the expected experimental error. Due to experimental difficulties the cage angular velocity could not be reliabily measured at high speeds. At low speeds, however, there is a fair agreement between the experimental data and the analytical predictions.

Application of Kinematically Compatible Rolling-Contact Pairs to the Design of Low-Friction Rocker-Pivots

1985 ◽  
Vol 107 (3) ◽  
pp. 388-393 ◽  
Author(s):  
M. Chew
Keyword(s):  
Rolling Contact ◽  
Friction Reduction ◽  
Valve Train ◽  
Rolling Motion ◽  
Rolling Element Bearings ◽  
Low Friction ◽  
Rolling Element ◽  
Highly Loaded

The concept of rolling-contact has been applied to reduce friction at highly loaded rocker-pivots without the use of rolling element bearings. Various configurations for a rolling motion at the pivot are discussed. As an example, this rolling-contact concept is applied to the pivot of a valve-train rocker. Problems relating to stability and motion distortion of the rocker are addressed and solved, resulting in significant friction reduction at the pivot.

Bearing Design and Lubrication

2021 ◽  
pp. 141-161
Author(s):  
Karl Kollmann ◽  
Calum E. Douglas ◽  
S. Can Gülen
Keyword(s):  
High Sensitivity ◽  
Journal Bearings ◽  
Lubricating Oil ◽  
Rolling Element Bearings ◽  
Complete Evaluation ◽  
Overall Design ◽  
Rolling Element ◽  
Oil Flow ◽  
Bearing Design ◽  
Outside Diameter

High rotational speeds of the impeller call for careful bearing design and layout, not just those on the supercharger impeller shaft itself but also on any preceding shafts, which may run at lower speed. The question of whether to use plain (journal) bearings or rolling element bearings can only be decided after a complete evaluation of the overall design of the supercharger drive system in question. Journal bearings are in general smaller in outside diameter and despite the higher overall length have a lower weight than rolling element bearings. Journal bearings demand several times the lubricating oil flow rate than rolling element bearings, and they also exhibit high sensitivity to particulates in the oil and the overall quality thereof.

Experimental investigation on time-domain features in the diagnosis of rolling element bearings by acoustic emission

2021 ◽  
pp. 107754632110161
Author(s):  
Aref Aasi ◽  
Ramtin Tabatabaei ◽  
Erfan Aasi ◽  
Seyed Mohammad Jafari
Keyword(s):  
Acoustic Emission ◽  
Condition Monitoring ◽  
Time Domain ◽  
Central Moment ◽  
Rolling Element Bearings ◽  
Test Rig ◽  
Acoustic Emission Sensor ◽  
Outer Race ◽  
Common Time ◽  
Rolling Element

Inspired by previous achievements, different time-domain features for diagnosis of rolling element bearings are investigated in this study. An experimental test rig is prepared for condition monitoring of angular contact bearing by using an acoustic emission sensor for this purpose. The acoustic emission signals are acquired from defective bearing, and the sensor takes signals from defects on the inner or outer race of the bearing. By studying the literature works, different domains of features are classified, and the most common time-domain features are selected for condition monitoring. The considered features are calculated for obtained signals with different loadings, speeds, and sizes of defects on the inner and outer race of the bearing. Our results indicate that the clearance, sixth central moment, impulse, kurtosis, and crest factors are appropriate features for diagnosis purposes. Moreover, our results show that the clearance factor for small defects and sixth central moment for large defects are promising for defect diagnosis on rolling element bearings.

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