scholarly journals Influence of Contamination of Gear Oils in Relation to Time of Operation on Their Lubricity

2021 ◽  
Vol 11 (24) ◽  
pp. 11835
Author(s):  
Leszek Gil ◽  
Krzysztof Przystupa ◽  
Daniel Pieniak ◽  
Edward Kozłowski ◽  
Katarzyna Antosz ◽  
...  
Keyword(s):  
Solid Particles ◽  
Friction Reduction ◽  
Test Results ◽  
Oil Viscosity ◽  
Heavy Trucks ◽  
History Of ◽  
Gear Oil ◽  
Wear Products ◽  
Gear Oils ◽  
Time Of Operation

The quality and reliability of consumables, including gear oils, results in the failure-free operation of the transmission components in heavy trucks. It is known that oil viscosity is essential for all lubricated tribopairs for wear and friction reduction in all vehicles with a gearbox. Viscosity may be influenced by the contamination that wear products can impart on the oil. Oil contamination can also affect lubrication efficiency in the boundary friction conditions in gearboxes where slips occur (including bevel and hypoid gearboxes). The present research focused on this issue. An obvious hypothesis was adopted, where it was theorized that exploiting the contaminants that are present in gear oil may affect how the lubricating properties of gear oils deteriorate. Laboratory tests were performed on contaminants that are commonly found in gear oil using the Parker Laser CM20. The study was designed to identify a number of different solid particles that are present in oil. At the second stage, friction tests were conducted for a friction couple “ball-on-disc” in an oil bath at 90 °C on a CSM microtribometer. The quantitative contamination of the gear oils that contained solid particles and the curves representing the friction coefficients of fresh oils with a history of exploitation were compared. The test results were statistically analysed. Exploitation was shown to have a significant impact on the contamination of gear oils. It was revealed that the contamination and the mileage had no effect on the tested oils.

Gear oil influences on efficiency of gear and fuel economy of cars

2000 ◽  
Vol 214 (2) ◽  
pp. 189-196 ◽  
Author(s):  
W. J. Bartz
Keyword(s):  
Fuel Consumption ◽  
Fuel Economy ◽  
High Efficiency ◽  
Friction Reduction ◽  
Friction Modifiers ◽  
Oil Viscosity ◽  
Fuel Economy Improvement ◽  
Viscosity Grade ◽  
Gear Oil ◽  
Gear Oils

1. First of all, it should be considered that the fuel consumption of a car depends on a set of parameters only partly related to tribology. Their influence is much more pronounced than that of the lubricant. 2. Only the mechanical losses can be decreased by lubricant-related measures. Therefore, the fuel economy improvement that possibly might be realized is rather limited, especially when taking into account the rather high efficiency of gears. 3. When evaluating the influence of viscosity on fuel consumption, the so-called effective viscosity must be taken into account. This is most important for non-Newtonian oils. 4. Reducing the gear oil viscosity by one SAE viscosity grade will result in fuel consumption reductions of 0.2-1.5 per cent at high temperatures and 0.4-2.5 per cent at low temperatures. 5. Using friction modifiers in gear oils, fuel consumption reductions of between 1.0 and 6.0 per cent are realistic. 6. On the basis of a 50 per cent friction reduction maximum fuel consumption reductions between 1.0 and 5.1 per cent by other gear oils are possible, considering different driving programmes. 7. Tests with a real automobile gear resulted in fuel economy improvements of the order of magnitudes of 1 per cent by other gear oils. 8. The results of measurements confirm in principle the calculated estimations.

scholarly journals Abrasive Wear, Scuffing and Rolling Contact Fatigue of DLC-Coated 18CrNiMo7-6 Steel Lubricated by a Pure and Contaminated Gear Oil

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7086
Author(s):  
Waldemar Tuszyński ◽  
Remigiusz Michalczewski ◽  
Edyta Osuch-Słomka ◽  
Andrzej Snarski-Adamski ◽  
Marek Kalbarczyk ◽  
...  
Keyword(s):  
Abrasive Wear ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Solid Particles ◽  
Rolling Contact ◽  
Lubricating Oil ◽  
Gear Teeth ◽  
Ball Rolling ◽  
Gear Oil ◽  
Gear Oils

Due to extreme working conditions of mining conveyors, which contaminate gear oil with solid particles, their transmissions are exposed to intensive abrasion, scuffing, and even rolling contact fatigue (pitting). These effects shorten gear life. To prevent their occurrence, a wear-resistant coating can be deposited on gear teeth. The resistance to abrasive wear, scuffing, and pitting was investigated and reported in the article. Simple, model specimens were used. Abrasive wear and scuffing were tested using a pin-and-vee-block tribosystem in sliding contact. A cone–three-ball rolling tribosystem was employed to test pitting. The material of the test specimens (pins, vee blocks, cones) was 18CrNiMo7-6 case-hardened steel. Two types of DLC (Diamond-like Coatings) coatings were tested, W-DLC and W-DLC/CrN. The vee blocks and cones were coated. Two industrial gear oils were selected to lubricate the specimens: one with a mineral and one with a synthetic PAO (polyalphaolephine) base, as pure oil or contaminated with solid particles from a coal mine. The results show that, to minimize the tendency to abrasion, scuffing, and pitting of specimens made of 18CrNiMo7-6 steel, the W-DLC/CrN coating should be deposited. This coating also gives very good protection when the lubricating oil is contaminated.

scholarly journals Seroprevalence of SARS-CoV-2 Antibodies Among Health Care Personnel at a Health Care System in Pakistan

2021 ◽  
pp. 101053952110110
Author(s):  
Salma Abbas ◽  
Aun Raza ◽  
Ayesha Iftikhar ◽  
Aamir Khan ◽  
Shahzaib Khan ◽  
...  
Keyword(s):  
Health Care ◽  
Control Measures ◽  
Health Care Personnel ◽  
Test Results ◽  
Antibody Testing ◽  
Chain Reaction ◽  
Past Infection ◽  
Infection Control Measures ◽  
History Of ◽  
Polymerase Chain

Health care personnel (HCP) are at high risk for coronavirus disease-2019 acquisition. Serum antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) indicate past infection. Our institution offered SARS-CoV-2 antibody testing to HCP. We surveyed HCP with positive test results to explore past exposure to SARS-CoV-2, details of symptoms during the preceding 6 months, and a history of SARS-CoV-2 polymerase chain reaction testing. A total of 2162 HCP underwent antibody testing. Eight hundred fifty-seven (39.6%) employees tested positive and, of these, 820 (95.7%) participated in the survey. When adjusted for age, males had higher odds of testing positive for SARS-CoV-2 antibodies compared with females (OR = 1.68; 95% CI = 1.37-2.05; P = .00) and clinical staff had higher odds of SARS-CoV-2 seropositivity compared with nonclinical staff (OR = 1.273; 95% CI = 1.06-1.53; P = .01). Implementation of effective infection control measures is essential to protect HCP from coronavirus disease-2019.

scholarly journals Clinical judgement in chest pain: a case report 

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Mishita Goel ◽  
Shubhkarman Dhillon ◽  
Sarwan Kumar ◽  
Vesna Tegeltija
Keyword(s):  
Chest Pain ◽  
Coronary Artery ◽  
Tobacco Use ◽  
Stress Test ◽  
Artery Bypass ◽  
Pretest Probability ◽  
Clinical Judgement ◽  
Test Results ◽  
Cardiac Stress ◽  
History Of

Abstract Background Cardiac stress testing is a validated diagnostic tool to assess symptomatic patients with intermediate pretest probability of coronary artery disease (CAD). However, in some cases, the cardiac stress test may provide inconclusive results and the decision for further workup typically depends on the clinical judgement of the physician. These decisions can greatly affect patient outcomes. Case presentation We present an interesting case of a 54-year-old Caucasian male with history of tobacco use and gastroesophageal reflux disease (GERD) who presented with atypical chest pain. He had an asymptomatic electrocardiogram (EKG) stress test with intermediate probability of ischemia. Further workup with coronary computed tomography angiography (CCTA) and cardiac catheterization revealed multivessel CAD requiring a bypass surgery. In this case, the patient only had a history of tobacco use but no other significant comorbidities. He was clinically stable during his hospital stay and his testing was anticipated to be negative. However to complete workup, cardiology recommended anatomical testing with CCTA given the indeterminate EKG stress test results but the results of significant stenosis were surprising with the patient eventually requiring coronary artery bypass grafting (CABG). Conclusion As a result of the availability of multiple noninvasive diagnostic tests with almost similar sensitivities for CAD, physicians often face this dilemma of choosing the right test for optimal evaluation of chest pain in patients with intermediate pretest probability of CAD. Optimal test selection requires an individualized patient approach. Our experience with this case emphasizes the role of history taking, clinical judgement, and the risk/benefit ratio in deciding further workup when faced with inconclusive stress test results. Physicians should have a lower threshold for further workup of patients with inconclusive or even negative stress test results because of the diagnostic limitations of the test. Instead, utilizing a different, anatomical test may be more valuable. Specifically, the case established the usefulness of CCTA in cases such as this where other CAD diagnostic testing is indeterminate.

High Efficient Viscoelastic Damper for Heavy Trucks

2012 ◽  
Vol 215-216 ◽  
pp. 318-321 ◽  
Author(s):  
Sai Fei Zhang ◽  
Xiao Ling Liu ◽  
Yong Liu
Keyword(s):  
Flow Rate ◽  
Viscous Damping ◽  
Calculation Formula ◽  
Performance Curve ◽  
Test Results ◽  
Viscoelastic Damper ◽  
Damping Force ◽  
Heavy Trucks ◽  
High Efficient ◽  
Damper Design

In this paper, a new viscoelastic damper design for heavy trucks is presented and a calculation formula of viscous damping force considering the effect of Viscoelastic Fluids (VF) flow rate is carried out. By numerically simulating this equation, curves of the viscoelastic damper performance curve is obtained, and the results show that theoretical calculation result and the test results are well consistent, with the exception at the start point. Theoretical curves are more plumpness in compared with test curves.

scholarly journals Hubungan Mean Arterial Pressure (MAP) Dengan Preeklamsia Pada Ibu Hamil Di Puskesmas Bontobangun Kabupaten Bulukumba

2020 ◽  
Vol 5 (2) ◽  
pp. 138-145
Author(s):  
Ely Kurniati ◽  
Rusnawati
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Pregnant Women ◽  
Sampling Method ◽  
Blood Pressure Measurement ◽  
Test Results ◽  
Historical Cohort ◽  
Measurement Results ◽  
History Of ◽  
The Mean

Preeclampsia complicates 4-7% of pregnancies and remains the leading cause of maternal and fetal morbidity and mortality worldwide. Despite improvements in health care over the last decade, preeclampsia remains the second most common cause of maternal mortality in Indonesia. This study aims to determine whether the mean arterial pressure (MAP) is related to the incidence of preeclampsia in pregnant women at the Bontobangun Puskesmas, Bulukumba district for the period 2018 to 2019. This research uses a descriptive-analytic approach with Historical Cohort Studies, namely by looking at the cohort book of the history of blood pressure measurement results for pregnant women at the Bontobangun Public Health Center, Bulukumba Regency for the period 2018 to 2019. Determining the sample using the sampling method taken by purposive sampling. 31 samples of pregnant women who experienced preeclampsia and 31 controls were pregnant women with normal conditions who had certain criteria (matching) with the sample. The results explained that from the paired T-test results, the value of α> 0.037 so that it is said that there is a relationship between mean artery pressure (MAP) and the incidence of preeclampsia in pregnant women at Bontobangun puskesmas for the period 2018-2019.

scholarly journals An Overview of Heavy Trucks/Buses Braking Performance

1991 ◽  
Vol 8 (1) ◽  
Author(s):  
Richard M. Ziernicki
Keyword(s):  
Statistical Data ◽  
Vehicle Speed ◽  
Test Results ◽  
Heavy Duty ◽  
Braking Performance ◽  
Emergency Braking ◽  
Heavy Trucks ◽  
Brake Performance ◽  
Drag Factor ◽  
Heavy Duty Vehicles

The writer discusses the performance of heavy duty vehicles during emergency braking. The paper reviews statistical data related to the trucking accidents, and discusses brake performance, tires, and the stopping ability of heavy duty vehicles. Relationships between drag factor, coefficient of friction, vehicle speed, type of tire, road surface, brake design, and brake temperature are discussed. Some of the test results performed on heavy trucks are presented. The discussion is general in order to make the presentation useful both to practicing reconstruction specialists, and to attorneys.

scholarly journals Case Report: Two Cases of Subacute Thyroiditis Following SARS-CoV-2 Vaccination

2021 ◽  
Vol 8 ◽  
Author(s):  
Catherine Bornemann ◽  
Katharina Woyk ◽  
Caroline Bouter
Keyword(s):  
Viral Infections ◽  
Clinical Laboratory ◽  
Previous History ◽  
Subacute Thyroiditis ◽  
Clinical Test ◽  
Thyroid Disorders ◽  
Thyroid Disorder ◽  
Lateral Neck ◽  
Test Results ◽  
History Of

Subacute thyroiditis is an inflammatory thyroid disorder associated with viral infections. Rare cases of subacute thyroiditis have also been described following vaccination. Recently, a few cases of subacute thyroiditis following SARS-CoV-2 vaccination have also been reported. Here, we present two cases of cytological proven subacute thyroiditis after receiving the first dose of a SARS-CoV-2 vaccination. We describe clinical, laboratory, imaging and cytological findings in two cases of subacute thyroiditis that presented in our department 2 weeks after SARS-CoV-2 vaccination with Spikevax (Moderna Biotech, Spain) and Vaxzevria (AstraZeneca; Sweden). Both cases did not have a previous history of thyroid disorders and presented with anterior and lateral neck pain. Clinical test results as well as cytological findings were consistent with subacute thyroiditis. Subacute thyroiditis may develop following a SARS-CoV-2 vaccination and should be considered as a possible side effect in cases that present with thyroid pain.

scholarly journals The Effect of a Gear Oil on Abrasion, Scuffing, and Pitting of the DLC-Coated 18CrNiMo7-6 Steel

Coatings ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 2 ◽  
Author(s):  
Remigiusz Michalczewski ◽  
Marek Kalbarczyk ◽  
Anita Mańkowska-Snopczyńska ◽  
Edyta Osuch-Słomka ◽  
Witold Piekoszewski ◽  
...  
Keyword(s):  
Simple Model ◽  
Mineral Oil ◽  
Hardened Steel ◽  
Crn Coating ◽  
Gear Teeth ◽  
Hard Particles ◽  
Polyalkylene Glycol ◽  
Gear Oil ◽  
Gear Oils ◽  
Harsh Conditions

The transmissions of mining conveyors are exposed to very harsh conditions. These are primarily related to the contamination of the gear oil with hard particles coming from coal and lignite, which can cause intensive abrasive wear, scuffing, and even pitting, limiting the life of gears. One of the ways to prevent this problem is the deposition of a wear-resistant coating onto gear teeth. However, a proper choice of gear oil is an important issue. The abrasion, scuffing, and pitting tests were performed using simple, model specimens. A pin and vee block tester was employed for research on abrasion and scuffing. To test pitting, a modified four-ball pitting tester was used, where the top ball was replaced with a cone. The test pins, vee blocks, and cones were made of 18CrNiMo7-6 case-hardened steel. A new W-DLC/CrN coating was tested. It was deposited on the vee blocks and cones. For lubrication, three commercial industrial gear oils were used: A mineral oil, and two synthetic ones with polyalphaolefin (PAO) or polyalkylene glycol (PAG) bases. The results show that, to minimize the tendency forabrasion, scuffing, and pitting, the (W-DLC/CrN)-8CrNiMo7-6 tribosystems should be lubricated by the PAO gear oil.

scholarly journals Primary splenic hydatidosis: a case report

2019 ◽  
Vol 48 (2) ◽  
pp. 030006051984550
Author(s):  
Qiang Wang ◽  
Ming-quan Pang ◽  
Ying-li Kang ◽  
Zhi-xin Wang ◽  
Dongzhi Cairang ◽  
...  
Keyword(s):  
Case Report ◽  
Laparoscopic Splenectomy ◽  
Serological Test ◽  
Chronic Atrophic Gastritis ◽  
Pathological Examination ◽  
Test Results ◽  
Imaging Findings ◽  
Pastoral Area ◽  
History Of

We herein report a case of primary splenic hydatidosis to provide data regarding the diagnosis, treatment, and epidemiological statistics of this disease. The patient was from a pastoral area and was diagnosed with primary splenic hydatidosis with chronic atrophic gastritis. The patient had no history of surgical treatment of hydatidosis. The diagnosis was mainly based on possible exposure to endemic areas, imaging findings, serological test results, and operative and pathological examination findings. Laparoscopic splenectomy was performed, and regular albendazole therapy was given after the operation. The patient was admitted to the hospital for gastrointestinal bleeding 3 months postoperatively, and she was successfully treated and discharged. No recurrence of hydatid foci has been observed since the follow-up.

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