bluuebunny/crossref_metadata_2025 huggingface dataset:
Folding kinetics and thermodynamics of Pseudomonas syringae effector protein AvrPto provide insight into translocation via the type III secretion system
Authors: Dawson Jennifer E. , Nicholson Linda K.
Published: June 2008

In order to infect their hosts, many Gram‐negative bacteria translocate agents of infection, called effector proteins, through the type III secretion system (TTSS) into the host cytoplasm. This process is thought to require at least partial unfolding of these agents, raising the question of how an effector protein might unfold to enable its translocation and then refold once it reaches the host cytoplasm. AvrPto is a well‐studied effector protein of Pseudomonas syringae pv tomato. The presence of a readily observed unfolded population of AvrPto in aqueous solution and the lack of a known secretion chaperone make it ideal for studying the kinetic and thermodynamic characteristics that facilitate translocation. Application of Nzz exchange spectroscopy revealed a global, two‐state folding equilibrium with 16% unfolded population, a folding rate of 1.8 s−1, and an unfolding rate of 0.33 s−1 at pH 6.1. TrAvrPto stability increases with increasing pH, with only 2% unfolded population observed at pH 7.0. The R1 relaxation of TrAvrPto, which is sensitive to both the global anisotropy of folded TrAvrPto and slow exchange between folded and unfolded conformations, provided independent verification of the global kinetic rate constants. Given the acidic apoplast in which the pathogen resides and the more basic host cytoplasm, these results offer an intriguing mechanism by which the pH dependence of stability and slow folding kinetics of AvrPto would allow efficient translocation of the unfolded form through the TTSS and refolding into its functional folded form once inside the host.
Cardiovascular events in survivors of high‐dose chemotherapy for germ cell tumors
Authors: Ishioka Jun‐Ichiro , Fujii Yasuhisa , Kageyama Yukio , Fukuda Hiroshi , Higashi Yotsuo , Kihara Kazunori
Published: June 2008

Abstract:  The objective was to investigate cardiovascular complications in long‐term survivors treated by high‐dose chemotherapy. We analyzed 13 previously successfully treated metastatic germ cell cancer patients. The patients ranged in age from 16 to 38 years (median: 27 years). Patients were treated by high‐dose ifosfamide, carboplatin and etoposide (ICE) or high‐dose etoposide, ifosfamide and cisplatin (VIP). In a minimal follow‐up of 48 months, the incidence of cardiovascular events and the accumulated doses of platinum were analyzed from the total amounts of cisplatin and/or carboplatin. The calculated accumulated doses of platinum ranged from 487 to 4302 mg (median: 2297 mg). Cardiovascular events were observed in two patients who received cumulative doses of more than 3000 mg of platinum. Survivors of high‐dose chemotherapy may have a risk of developing cardiovascular complications during the early phase of follow‐up. In particular, patients who have received carboplatin‐based high dose chemotherapy require careful observation.
Modified foreskin reconstruction for distal hypospadias and chordee without hypospadias
Authors: Hayashi Yutaro , Kojima Yoshiyuki , Mizuno Kentaro , Maruyama Tetsuji , Tozawa Keiichi , Kohri Kenjiro
Published: June 2008

Abstract:  Although foreskin reconstruction was established for hypospadias surgery in Europe two decades ago, it appears to introduce an extra risk of postoperative complications. We modified foreskin reconstruction in order to reduce the complications caused by its use. After correction of penile curvature and urethroplasty, the inner mucosal layer of the foreskin was separated from the outer skin layer. The approximation of each layer in the midline was limited and transverse adaptation was added to the remaining portion. We carried out the modified foreskin reconstruction for 11 patients and no patients developed postoperative complications. After the foreskin reconstruction, the glans, which was concealed by the reconstructed foreskin, was easily exposed by retracting the foreskin.
Skin flap technique for the reconstruction of a deep ureteral stomal obstruction
Authors: Hiratsuka Yoshiharu , Ishii Tatsu , Taira Hiroshi , Oonishi Hiroshige
Published: June 2008

Abstract:  Cutaneous ureterostomy is a minimally invasive urinary diversion procedure but postoperative stomal stenosis is a major problem. We describe a simple stomal reconstruction technique using a skin flap for the correction of deep ureteral stomal obstruction after cutaneous ureterostomy.
Taxonomic studies of Pterostichus ishikawai Nemoto (Coleoptera: Carabidae)
Authors: SASAKAWA Kôji , KIM Jung‐Lark , KIM Jong‐Kuk , KUBOTA Kôhei
Published: June 2008

A macrocephalic pterostichine carabid, Pterostichus ishikawai Nemoto, endemic to the Korean Peninsula, is taxonomically revised based mainly on the membranous parts of the genitalia (male endophallus and female vagina). Two species are separated from P. ishikawai (type locality: Mount Taebaegsan) and newly described: P. ishikawaioides (type locality: Mount Sobaeksan) and P. jiricola (type locality: Mount Jirisan). Since comparative male genital morphology does not support monophyly for these three species, the two novel species should be treated as distinct species, not subspecies of P. ishikawai.
Performance of clones and morphs of two cereal aphids on wheat plants with high and low nitrogen content
Authors: KHAN Mahfuza , PORT Gordon
Published: June 2008

The great variability of the aphid life cycle and their tendency for host alternation gives rise to aphid clones and morphs. Inter‐ and intraclonal variability may be observed in the responses of aphids to various environmental factors. In this study we aimed to evaluate the influence of intrinsic factors (clone and morph type) on the intrinsic rate of increase (rm) of the English grain aphid, Sitobion avenae (Fabricius), and the bird cherry‐oat aphid, Rhopalosiphum padi (Linnaeus). For each species four apterous clones were collected from established laboratory colonies and compared to assess their relative fitness on high‐ and low‐nitrogen wheat plants under laboratory conditions. The clones had significantly different intrinsic rates of increase on high‐ and low‐nitrogen plants. All R. padi clones had a higher intrinsic rate of increase and mean relative growth rate than S. avenae. Experiments were also conducted to compare the mean fecundity of apterous and alate morphs of S. avenae and R. padi clones on high‐ and low‐nitrogen wheat plants. On high‐nitrogen plants the apterous morphs of S. avenae clones had significantly higher mean fecundity than alate morphs. There were no significant differences between the mean fecundity of alate morphs of the same species on high‐ and low‐nitrogen plants. The results support the idea of better fitness of specific clones/morphs on certain host plants due to higher and lower intrinsic rates of increase.
Effect of intrauterine treatment with cephapirin on the reproductive performance of seasonally calving dairy cows at risk of endometritis following periparturient disease
Authors: Runciman DJ , Anderson GA , Malmo J , Davis GM
Published: June 2008

Objective To determine the effect of intrauterine cephapirin (0.5 g) treatment on the reproductive performance of cows diagnosed as at risk of developing endometritis.

Methods Cows (n = 1325) from 17 seasonal calving dairy herds were enrolled if they had been calved for more than 6 days and had a condition that placed them at risk of endometritis. Half were treated with intrauterine cephapirin at an examination performed 28–37 days prior to mating start date (MSD). Cows were scored for body condition, their vaginal discharge was scored using vaginoscopy (VV), and the uterus and ovaries were assessed by rectal palpation.

Results Overall, there was no significant treatment effect on reproductive performance. In 945 modified at risk (MAR) cows the effect of treatment varied with the calving to treatment interval (CTI) and VV status. For the subset of 229 MAR cows with CTI ≤ 28 days, treatment improved the proportions of first‐service conception (OR 3.1; P < 0.01) and 6‐week in‐calf (OR 2.1; P < 0.05), and reduced the mean MSD to conception interval by 20 days (P < 0.05). The difference was greater in cows with a positive VV score (1–3). Treated VV‐negative cows with CTI > 48 days had a reduced proportion of cows in‐calf by 6 weeks (OR 0.58; P = 0.056) compared with untreated cows.

Conclusion Intrauterine cephapirin infusion of MAR cows improved reproductive performance, depending on CTI. The greater treatment effect in VV‐positive cows suggests that VV scoring is a useful tool for the diagnosis of endometritis.
Quantification of VEGF‐C expression in canine mammary tumours
Authors: Qiu C , LIN DD , Wang HH , Qiao CH , Wang J , Zhang T
Published: June 2008

Background  Tumours release angiogenic factors such as vascular endothelium growth factor (VEGF), which induces growth of a capillary network around the tumour. Elevated concentrations of VEGF have been reported in human mammary gland tumours.

Methods  To evaluate the expression of VEGF‐C mRNA in canine mammary tissue, 38 mammary gland tumours (including 15 benign and 23 malignant mammary tumours), and 4 normal mammary glands were investigated by real‐time reverse transcriptase quantitative polymerase chain reaction.

Results  VEGF‐C expression in the malignant mammary tumours was much higher than in the benign mammary tumours or normal mammary tissue (P < 0.001). The expression of VEGF‐C in tumours with lymph node metastasis was much higher than in those without (P < 0.01).

Conclusion  The level of expression of VEGF‐C did not correlate with tumour size or the patient's age, but was significantly higher in malignant mammary tumours and related to lymph node metastasis, making it a candidate marker for predicting metastasis of canine mammary cancer.
p16, cyclin D1, and human telomerase reverse transcriptase expression in cervical premalignant and malignant lesions
Authors: Chang Sunhee , Joo Mee , Kim Hanseong
Published: June 2008

Background and aim: Although morphological criteria are important for diagnosis of cervical intraepithelial neoplasia, it is not possible to differentiate those that will regress from those that will progress into invasive cancer. We evaluate the usefulness of p16, cyclin D1, and human telomerase reverse transcriptase (hTERT) as diagnostic and prognostic biomarkers in cervical lesions. Methods: We studied 12 cases of benign lesion, 15 cases of low‐grade squamous intraepithelial lesion, 46 cases of high‐grade squamous intraepithelial lesion, and 13 cases of squamous cell carcinoma by immunohistochemistry. Results: The p16 expression was significantly correlated with high risk‐human papillomavirus (HR‐HPV) status, lesion grade, and decreased cyclin D1 expression. The decreased cyclin D1 expression was significantly correlated with HR‐HPV status, lesion grade, and p16 expression. The positive predictive values for high grade lesion of p16 expression, HR‐HPV status, and decreased cyclin D1 expression were 93.8%, 81.3%, and 51.2%, respectively. The distribution pattern of hTERT positive cells was correlated with morphologically dysplastic cells. Conclusions: A good correlation was observed between cervical lesion grade and p16 expression, decreased cyclin D1 expression, and HR‐HPV status. p16 expression could be used as a diagnostic and prognostic biomarker for risk of developing cervical cancer in women infected with HPV.
Immunohistological study of skin involvement in Kikuchi's disease
Authors: Lee Hyekyung , Oh Shintaek , Kim Myungsuk , Shin Soyoung , Park Meeja
Published: June 2008

We describe the immunohistochemical findings of the skin lesion of Kikuchi's disease (KD) in two patients. They presented with fever, lymphadenopathy, and eruptions on the skin of palm and face. Each patient had a lymph node biopsy which showed the typical necrotizing lymphadenitis of KD. Skin biopsies from the two patients showed various pathologic findings of a crusted epidermis, a dense lymphohistiocytic perivascular and interstitial infiltrate, and abundant karyorrhectic debris with an absence of neutrophils, paralleling the nodal histology in KD. Immunohistochemically, the lymphohistiocytic cells in the skin and lymph nodes showed similar positivity for CD68, CD3, CD8, granzyme B and negativity for CD20 and CD4. These findings suggest that the cytotoxic T lymphocytes play important roles in the skin and lymph node without the significant assistance of B and helper T lymphocytes.
Monte Carlo Simulation of Tests for the Determination of Gear Design Allowable Stresses
Authors: Amorena M. , Barsanti M. , Gubinelli M. , Vitali M.
Published: June 2008

In this work the design of fatigue test experiments to be performed on a new high-speed gear test rig is discussed. Several methods are compared and an optimal design is derived using a new statistical criterion of analysis. The main problem is to determine the minimum number of gears to be tested in order to obtain, with a given confidence level, correct indications of the distribution of bending and pitting fatigue resistance of such test gears. To solve this problem the most efficient experimental method has to be chosen first. From the statistical point of view the fatigue resistance is a random quantity that cannot be directly sampled. The methods currently used for the estimate of the distribution of this quantity are based on sequential tests like the stair-case (or up-down) method and its variants. In this paper we analyze the performance of a set of these methods by means of Monte-Carlo (MC) simulations. The emphasis is on the identification of an efficient procedure to estimate both the mean and the standard deviation of the unknown resistance distribution of the gears. Efficiency is here understood in terms of the amplitude of the confidence intervals at fixed confidence level when the size of the samples is relatively small (10–30). Finally, a Combined Robbins-Monro Random Step (CRMRS) method is herein proposed. The CRMRS method, for its stability, proved to be most suitable among the methods we considered when a-priori estimates for the mean and the standard deviation are not available. This is indeed the case when dealing with new materials. Moreover the CRMRS method achieves the best accuracy in the estimation of the variance. A similar but separated investigation has been performed for the case of gear scuffing tests. A sampling method, that can be used to reduce the number of inspections necessary to estimate (at a given confidence level) the minimum load at which scuffing takes place, is here proposed.
A Study on Jumping Characteristics in Synchronous Belt Drives: Experimental Results and FE Analysis at Driven Pulley Jumping
Authors: Koyama Tomio , Zhang Weiming , Kagotani Masanori , Ueda Hiroyuki
Published: June 2008

The jumping characteristics at the driven pulley of L type synchronous belt drives are experimentally and analytically discussed. The number of the driving and the driven pulley teeth is the same and the wrapping angle of the belt on both pulleys is π radian. In this paper, the meshing state of belts on both of the driving and driven pulleys just before jumping is analyzed using the Finite Element analysis. Standardized L type synchronous belts and pulleys are used for analysis and experiments of the meshing states between belt and pulley, load distribution stress analysis and jumping torque. A 337L075 trapezoidal tooth profile synchronous belt and a 36L075 synchronous pulley are used in the analysis and the experiments. The wrapping angle of belt on both the driving and the driven pulley is equal to π radian. “ABAQUS/Standard” is used for the simulation and analysis of the belt. The simulation of the FE analysis of the wrapping angle of the belt on the driven pulley is almost the same with the experimental result. FE analysis of the load distribution just before jumping on the driven pulley agrees well with the experimental results.
Effect of Tooth Deflection and Corner Contact on Backside Separation (Backlash) of Gear Pairs
Authors: Eritenel Tugan , Houser Donald R. , Vijayakar Sandeep M. , Casella James M.
Published: June 2008

Because plastic materials have moduli that are much lower than those of metals, the deflections of loaded plastic gears are much greater than those of steel gears. This paper presents an evaluation of tooth deflections and the effect of load on the backlash of these gears using a finite element program that has an accurate contact deflection analysis embedded within it. In addition to deflection analysis, the effect of tip modification on the contact regime and loads along the edges of the plastic gears is presented. An example spur gear pair and an example helical gear pair are used to demonstrate the analysis methodology. The results of the analysis show that backside tooth contact does not occur as tooth deflections in plastic gears increase with increasing load. In fact, the backside gap actually increases with increasing load.
Load Bearing Capacity of Super-Carburized Gears
Authors: Koide Takao , Tsubokura Koji , Oda Satoshi , Namba Chiaki
Published: June 2008

This paper describes a study on the load bearing capacity of super-carburized gears. Test gears and rollers of MAC14 and SCM415 steels were super or eutectoid-carburized under different carburizing conditions. The impact and bending fatigue tests for test gears and the contact fatigue test for test rollers were carried out. The effects of case depths on the impact and bending fatigue strengths of gears and the surface durability of rollers were determined. The impact breaking limit energy of super-carburized gears was found to be larger by about 15% than that of eutectoid-carburized gears irrespective of case depth. The bending fatigue strength of the super-carburized gear was found to be almost equal to that of the eutectoid-carburized gear. The surface durability of the super-carburized roller becomes larger with an increase of case depth and is larger than that of eutectoid-carburized rollers in the case of larger case depth. The surface failure modes for super and eutectoid-carburized rollers were spalling. The load bearing capacity of super and eutectoid-carburized gears was found to become larger by shot-peening.
A Testing Device for Fatigue Crack Propagation Experiments on Bevel and Face Gears
Authors: Filippini Mauro , Gorla Carlo
Published: June 2008

A testing device for performing single tooth bending fatigue tests on bevel and face gears is presented. Basically, it works as a normal gearbox in which the pinion acts as loading element while the gear wheel is kept fixed to the frame. The entire rig is installed in a servo-hydraulic torsion fatigue testing machine, so that torque amplitudes up 2200 Nm may be applied with convenient loading frequencies. Torque amplitude is measured by connecting the testing rig to the load cell of the testing machine. It’s possible to rotate the gearwheel at fixed positions so that a large number of teeth of the same wheel may be tested. If the tests are performed on teeth weakened by pre cracking, no special pinion is requested. The proposed testing rig may be employed for testing both bevel and face gears, by simply adapting the parts that keep the gearwheel fixed with the frame and by choosing the proper meshing pinion.
Transmission Error in Helical Synchronous Belt Drives in Bidirectional Operation: Influence of Pulley Flange Under No Load
Authors: Kagotani Masanori , Makita Kenichi , Ueda Hiroyuki , Koyama Tomio
Published: June 2008

Helical synchronous belt drives are more effective than conventional synchronous belt drives with respect to reducing noise and transmission error per single pitch of the pulley. However, the helix angle of the tooth trace causes axial belt movement. Therefore, a flanged pulley is used in a helical synchronous belt drive. In the present study, the transmission error in a helical synchronous belt drive using a flanged pulley under installation tension was investigated both theoretically and experimentally for the case where the pulley was rotated in bidirectional operation. The computed transmission error agrees well with the experimental results, thereby confirming the applicability of the proposed theoretical analysis for transmission error. In this case, transmission error is found to be generated by the difference in axial belt movement between the driving and driven sides, and by a change in the state of contact between the belt and pulley teeth flanks. The transmission error is reduced when the installation tension is set higher than the tension that causes a change in contact direction between the tooth flanks. In addition, transmission error does not occur when the driving and driven pulleys are of equal outside diameter and have no pulley alignment error.
Detection of Land Area Wear in Automotive Synchronous Belts
Authors: Johannesson Tomas
Published: June 2008

A common way of driving the camshafts of an internal combustion engine is by synchronous belt. One of the major drawbacks is their limited durability. Several failure modes may appear. This paper considers land area wear failures. The area between two teeth on a synchronous belt is called the land area. Most of the semicircular belt profiles, used in automotive cambelt drives today, have a small backlash, i.e. the pulley groove is a little wider than the belt tooth. This allows for a relative motion between belt and pulley teeth. In a cambelt drive, in which torques are oscillating, this is the case. The movement causes wear to the land area that eventually will lead to breakage of the facing fabric, forcing the belt-pulley contact to run on the belt cord which will quickly lead to belt failure. This paper describes a method to detect the wear of land areas of synchronous belts. From surface topology measurements of the land areas at different wear stages, well-known roughness parameters are used to determine the degree of wear. The roughness parameters variations are explained by a physical wear procedure. In addition to this formerly known land area wear originating from complete meshing, another wear mechanism was discovered present near the tooth roots. The newly discovered land area wear type can be explained by seating and unseating effects.
A Weight-Functions Based Approach to Predict Rolling Contact Fatigue Sub-Surface Crack Propagation in Gears
Authors: Guagliano Mario , Piazza Andrea , Vergani Laura
Published: June 2008

The problem of the rolling contact fatigue crack propagation in gear teeth is dealt with. An approach based on the weight function method for the determination of KI and KII of internal cracks was developed. The effect of the contact and of the friction between the crack faces was taken into consideration by using approximate relations. The results were compared with the ones obtained by finite element analyses and the agreement was found satisfactory. By means of the determined weight function several analyses were performed and an interpolating function of KII versus the crack length were found. An approach for rolling contact fatigue crack propagation prediction based on the obtained solution and on a short crack propagation law was developed and implemented in a computational routine. The results are critically discussed.
Gear Tooth Impact Testing
Authors: Rao S. B. , Noss R. C. , McPherson D. R. , DeMeter E. C.
Published: June 2008

It is very difficult, if not impossible, to estimate the impact resistance of gear teeth from standard impact test data. This is because of the in-homogenous nature of most gear teeth, with a high-Carbon case and a low-Carbon core, and its complex geometry. While gears are subject to impact loading in “real life” and current research efforts are significantly focused on developing alternate materials for gears, in a variety of applications, a need to characterize the impact resistance of a gear tooth under varying strain rates has consequently arisen. In order to meet this need an existing drop tower has been modified and instrumented to test gear teeth under varying strain rates to induce various modes of fracture. This paper describes the analytical model developed to represent the drop tower and the gear holding fixture, which was utilized to evaluate various design alternatives to design a system where strain rates could be varied. Based on the results of the model, a system was implemented and a preliminary set of impact tests conducted. While some dynamic problems were encountered, these tests show that the system is performing largely as required. The source of the dynamic problems encountered was also examined and changes to the system to overcome these problems are planned. Data obtained in the impact tests conducted will also be presented to demonstrate the capability of the system.
Modulation of Gear Tooth Loading Due to Traveling Wave Vibration
Authors: Talbert Paul B. , Gockel Richard R.
Published: June 2008

The first reduction gear set in a turboprop engine gearbox was changed from a spur configuration to helical in order to reduce dynamic load and tooth stress. During initial strain gage testing, a low frequency modulation (approximately 70 Hz) of the tooth engagement strain was observed. The modulation had not been present during previous strain gage tests of the gears in their original spur configuration. The expected decrease in dynamic load and tooth stress was not realized due to the low frequency modulation. Post test inspection revealed indications of end loading on both the forward and aft ends of the gear teeth. Additionally, a 22/rev standing wear pattern developed on the aft face of the bull gear rim where it contacts the high-speed pinion bearing thrust collar. Detailed analysis of the strain gage data coupled with traveling wave theory identified the source of the modulation as 19/rev response of a forward traveling three nodal diameter mode of the bull gear at approximately 2,500 Hz. An analytical simulation of the high-speed pinion tooth mesh multiplied by a signal representing a forward traveling three nodal diameter response of the bull gear exactly matched the observed modulation. Design-of-experiment engine tests using proximity probes to measure bull gear vibration identified improper contact at the bull gear thrust collar as the excitation of the three nodal diameter mode. A verification strain gage test with proper contact showed no modulation in tooth engagement.
Gear Finishing With a Nylon Lap
Authors: Nakae Masahiko , Hidaka Kazunori , Ariura Yasutsune , Matsunami Toshinori , Kohara Masao
Published: June 2008

The objective of this research is to develop a new lapping process which can efficiently make tooth flanks of hardened steel gears smooth as a mirror. The lapping is carried out using a nylon helical gear as a lap and a simple mechanical device. This paper first shows the lapping machine designed and manufactured by the authors and the procedure and principle of the lapping. And as a result of the lapping tests, it becomes clear that the process can make tooth flanks of hardened steel gears smooth in a short time and it is important to carry out the lapping for a short time using a nylon gear which has a large helix angle and high-teeth under a condition of high rotating speed and light load in order to prevent increases of tooth profile errors. Moreover the lapping process accompanied by micro vibrations of a nylon gear is tested. From the result, it is found that the addition of micro vibrations enables this process to reduce also tooth profile errors of work gears. The running noise and the load carrying capacity of lapped gears are considered.
Face Gearing With a Conical Involute Pinion: Part 2 — The Face Gear: Meshing With the Pinion, Tooth Geometry and Generation
Authors: Tan Jie
Published: June 2008

Definition of the face gearing with a conical involute pinion starts with the basic rack. The pinion and the face gear are obtained as the result of true conjugate generation, with generating action described by the equation of meshing. The limiting conditions of undercutting, interference and pointing on the face gear tooth are determined. A new method is proposed for continuous generation of the face gear with an intermediate member, which, together with state of the art CNC technologies, allows practical grinding, hobbing or shaving of the face gear. A mathematical model is established which relates the basic plane, the pinion, the intermediate member and the face gear with true conjugate action, thereby determining the relative position and motion between any two of the four members. Design considerations are discussed. A numerical example is given.
Face Gear Transmission Development Program at Sikorsky Aircraft
Authors: Binney David A. , Vinayak Harsh , Gmirya Yuiry , Zunski Lawrence M. , Houser D. R. , Ames E. C.
Published: June 2008

Sikorsky Aircraft, under a cooperative agreement with AATD (Aviation Applied Technology Directorate), has launched a four-year program, RDS-21 (Rotorcraft Drive Systems for the 21st Century), to develop face gear transmissions. RDS-21 addresses key technologies needed to enhance the drive systems of the objective force aircraft while developing new technologies to support the development of a new face gear drive system for Unmanned Air Vehicles (UAV) and the Future Utility Rotorcraft (FUR). Some of the initial funding for face gear development came from a partnership with Army MANTECH. This paper presents an overview of the RDS-21 face gear program and summarizes major milestones achieved to-date. Sikorsky has pursued face gear technologies by partnering with two key institutions. The GearLab at The Ohio State University has developed face gear analysis and design software while the other partner, Gleason Pfauter Inc., has developed face gear manufacturing technology. The methods developed for the design and analysis of face gears and some of the results of their application are covered in this paper. A mathematical model of the face gear generation process is created. The model facilitates the calculation of quantities of interest such as sliding velocities and contact ratio. Digital master gears are created for inspection purposes. A gear analysis software package is used to compute the loads and stresses in the gears. Work is continuing at The Ohio State University to create proprietary face gear analysis software for Sikorsky that can quickly run many design configurations.
Shaft Drive CVT: A New Type CVT Applying Crossed Axle Traction Drive
Authors: Yamanaka Masashi , Inoue Katsumi , Igari Genso , Narita Yukihito
Published: June 2008

The crossed axle traction drive developed by the authors is applied to a new mechanism of CVT, the Shaft Drive CVT. The input and output shafts with conical disks are parallel and a idler shaft having conical rollers at both ends is placed perpendicular to the input/output shafts. This idler shaft transmits a torque from the input shaft to the output shaft and its movement produces the speed variation by changing the contact point between the input/output disks and the idler rollers. The purposes of this study are 1) to propose the new CVT mechanism, 2) to design a curved shape of disk to decrease an amount of spin caused by the movement of contact point, 3) to develop a prototype to confirm the CVT to work and to evaluate the effect of curved disk by means of a power transmission efficiency. The design procedure of shapes of disk and roller are shown by geometrical analysis. The amount of spin is reduced 80% using the proposed concave disk. The range of speed changing ratio of the prototype is 0.5 to 2. The efficiency of 80% was obtained in case of input torque 10 Nm at uniform rate by using the conical disks. The effectiveness of concave disk is evaluated by comparing the experimental results using the conical and concave disks, respectively.
A Simplified Method for the Design of Narrow V-Belt Drives
Authors: Schaefer Frank H.
Published: June 2008

This paper describes a simplified method for the design of industrial-type narrow V-belt drives. The well-known design procedure takes place in several steps. It considers various parameters e.g. belt length, pulley diameter, ratio and slip, which affect the operational behavior of a belt drive. Experimental results show the influence of the position of the small and large pulley which lead to a difference in power capability as well as the influence of some operational parameters e.g slip or the pre-load. The reason for this difference is determined. The result leads to a change of procedure where the horsepower rating for the driven pulley is calculated assuming that the ratio is equal to 1. The value determined has to be corrected by means of the contact surface only, if the ratio is smaller or larger than 1.
Application of a System Level Model to Study the Planetary Load Sharing Behavior
Authors: Singh Avinash
Published: June 2008

In planetary transmissions, the input torque is split between a number of parallel sun-pinion-ring gear paths. Under ideal conditions, each parallel path carries the same amount of torque. However, manufacturing errors in the pinion pin-hole location cause unequal load sharing between the parallel paths. The nature of this load sharing behavior depends upon the number of pinions in the planetary system. This load sharing behavior is studied for 4, 5 and 6 pinion variants of a planetary transmission. Critical manufacturing tolerances are identified and loss function curves are generated. The effects of sun gear support stiffness, pinion needle bearing stiffness, and input torque on the load sharing results are also studied. It is shown that as the number of pinions in a planetary transmission increases, the pin-hole position error tolerance has to be tightened in order to reap the full benefits of load sharing between the pinions. Gear System Analysis Modules (GSAM) is an analytical tool that can model entire gear systems and will be used in this paper to quantify the load sharing between pinions. The numerical techniques implemented in GSAM will be briefly reviewed.
Dynamic Analysis of Sliding Friction in a Gear Pair
Authors: Gunda Rajendra , Singh Rajendra
Published: June 2008

Chief objective of this article is to evaluate the role of sliding friction in gear dynamics, and more specifically the effect of the periodic variations in mesh stiffness, load distribution and friction torque during a mesh cycle. A non-unity speed ratio spur gear is considered. Only the torsional degree of freedom of the gear pair, with ideal Coulomb friction law, is analyzed. Previous studies by Vaishya and Singh [1–3] make idealized assumptions about temporal (or spatial) variation of mesh stiffness and load sharing in order to obtain more tractable analytical solutions. In our formulation, an accurate Finite Element/Contact Mechanics analysis code [4] is run in the static mode to compute the mesh stiffness and load distribution at every time instant of the mesh. The computed parametric variation of stiffness is then incorporated into our dynamic formulation that includes frictional torques. Next, we use appropriate numerical techniques to solve for the dynamic response in time domain. This study, though preliminary in nature, examines the effects of pinion speed, coefficient of friction and mean input torque. This, along with work in progress, should yield further insights into the role of friction sources in gear vibro-acoustics.
A Study on Noise and Wear of Injection Molded Plastic Gears With Deformed Layer
Authors: Ohisa Tadayoshi , Shoji Akira , Sasaki Masanori , Inoue Katsumi
Published: June 2008

The injection molded plastic gears are widely used for rotation and power transmission for the reason of the low noise and the low cost. The deformed layer such as the skin layer appears easily in the tooth surface of the polyacetal gear. Therefore, authors studied the deformed layer actively applied in the two types of the low noise plastic gears. This paper describes the analysis and power examination of the polyacetal gears manufactured under the different molding conditions. The conclusion obtained are as following: (1) The temperatures difference of melted resin and the mold influences the hardness and the skin layer thickness of tooth. (2) The noise level becomes so low that the deformed layer produced for the gear’s tooth is thick. (3) The abrasive wear of gear is affected by the deformed layer, and the life of gear can be considered the moment when a noise level rose abnormally.
Investigation of the Noise and Vibration of Planetary Gear Drives
Authors: Chen Yong , Ishibashi Akira
Published: June 2008

With the aim of reducing the operating noise and vibration of the planetary gearsets used in automotive automatic transmissions, a meshing phase difference was applied to the planet gears that mesh with the sun and ring gears. Shaved and hardened helical gears with and without grinding were used as the component gears that were tested under varying rotational speeds and tooth loads. The experimental results clearly showed that planetary gearset noise and vibration were reduced when a meshing phase difference was applied.
Analytical Predictions for the Transmission Error Excitation in Various Multiple-Mesh Gear-Trains
Authors: Kartik V. , Houser Donald R.
Published: June 2008

Transmission error has long been considered the primary exciter of gear whine noise. Previous work has resulted in the development of an analytical procedure for contact analysis of gear meshing based on plate deflection models. This procedure has been demonstrated to give good accuracy while being much less computationally intensive than finite element models. This paper extends this procedure to predict the load distribution and transmission error in multiple-mesh gear-trains. The model takes into account the effect of the load distribution at one mesh, on the load distribution and transmission error on the other meshes. The local compliance at the meshes is calculated and the kinematic constraints are used to determine the contact points. The equations of contact are linearized and solved using a modified simplex algorithm. The effect of the ‘phasing’ of the meshes is also considered. Application areas of this analysis procedure include idler gears, planetary gear-trains and split-path transmissions.
Tooth Flank Corrections of Wide Face Width Helical Gears That Account for Shaft Deflections
Authors: Chang Shan , Houser Donald R. , Harianto Jonny
Published: June 2008

The tooth flank correction of power transmission helical gears with wide face width is studied by using a finite element based shaft deflection analysis program in conjunction with a numerical load distribution analysis procedure. The load distributions along the line of action, the elastic deflections and transmission errors of gear pairs are obtained by solving the equations of compatibility of displacement and equilibrium of forces. This paper discusses the influences of tooth flank corrections (tip relief, root relief, lead modification, end relief and their combinations) on gear stresses and transmission errors due to shaft deflections. The technique used in the paper has the capability of modeling all significant geometric and elastic contributions due to tooth contact of the pair being analyzed as well as other gears mounted on the same shafts. The results show that it is possible to optimize at the design stage the gear micro-geometry for minimum stresses and transmission errors without changing the gear macro-geometry.
Advanced Computer Modeling Technique in Gear Engineering
Authors: Goldfarb V. I. , Lunin S. V. , Trubachov E. S.
Published: June 2008

Universal low cost computer modeling technique for gear engineering is introduced. Modeling of shape formation and gear elements meshing is based on nowadays numerical methods invariant to gear type and method of its flank formation in combination with standard comprehensible packages of 3D modeling. The developed universal program blocks can be easily assembled to various options to solve different gear engineering problems. The application of the universal blocks can reduce the cost and simplify the development of complex gear related software packages. Detailed description of the technique, description of the problems and detailed step-by-step instruction for the numerical solution are introduced. Practical examples of the developed software application illustrate the possibilities of time and cost reduction for design, manufacture and meshing simulation for helical, spiral bevel, hypoid, worm, globoid and other gear drives.
Design of New Gear Tooth Profiles: Algorithm and Programming
Authors: Yeh Thomas , Yang Daniel C. H. , Tong Shih-Hsi
Published: June 2008

A new method for the design of line-contact gear profiles is introduced in this paper. In this method, the deviation function technique will be applied to generate the new gear profiles. Non-Uniform Rational B-Splines will be implemented as the deviation functions. Theory and algorithm of this method is implemented into an automatic software design package. Written in C language, this package is graphically interactive and PC based. According to design objective, many new conjugate profiles for gears or rotors can be obtained. Compared to current line-contact gears of involute profiles, some of these new profiles could achieve greater average profile conformity, which results in decreased contact stresses, and could also achieve decreased bending stresses. Since these gears are capable of carrying higher loads than gears of equivalent sizes, there should be cost savings and reduced machine sizes in certain special applications.
A Generalized Kinematics and Power Flow Analysis Methodology for Automatic Transmission Gear Trains
Authors: Kahraman A. , Kienzle K. , Zini D. M.
Published: June 2008

A generalized formulation for analyzing speeds and forces of the gear components of planetary automatic transmissions is proposed. The formulation is capable of analyzing any typical one-degree-of-freedom automatic transmission gear train containing any number of simple, compound or complex-compound planetary gear sets. It consists of three components: a kinematic analysis formulation, a gear ratio and kinematic configuration search algorithm, and a power flow analysis formulation. The kinematics module computes rotational speeds of gears and carriers. Given the type and number of planetary gear sets, the search module determines all possible kinematic configurations and gear tooth count combinations that result in a required set of gear ratios while eliminating all kinematic redundancies and unfavorable clutching sequences. The third component, the power-flow analysis formulation, performs a complete static force (power flow) analysis to determine all gear and bearing forces, and clutch and connection torque values. A five-speed transmission example is considered to highlight the capabilities of the proposed formulation.
Gear Diagnosis by Stress Wave Analysis
Authors: Board David B.
Published: June 2008

Stress Wave Analysis (SWAN) provides real-time measurement of friction and mechanical shock in operating machinery. This high frequency acoustic sensing technology filters out background levels of vibration and audible noise, and provides a graphic representation of machine health. By measuring shock and friction events, the SWAN technique is able to detect wear and damage at the earliest stages, and track the progression of a defect throughout the failure process. This is possible because as the damage progresses, the energy content of friction and shock events increases. This ‘stress wave energy’ is then measured and tracked against normal machine operating conditions. This paper describes SWAN theory of operation, as well as case histories on several diverse types of aircraft and industrial gears. It documents SWAN’s ability to: 1) accurately detect a broad range of discrepant conditions: and 2) to characterize the severity of damage. Examples include tooth wear, tooth spalling, tooth breakage, and web cracks.
Understanding Vibration Spectra of Planetary Gear Systems for Fault Detection
Authors: Mosher Marianne
Published: June 2008

This paper explores the vibration spectra for planetary gear systems by studying a kinematic model of vibration and comparing the model with measurements of two helicopter transmissions made in flight. The model and flight data include systems with both uniformly and nonuniformly spaced planet gears. This model predicts vibration to occur only at frequencies that are integer multiples of the planet spacing repetition frequency and clustered around gear mesh harmonics. Vibration measurements show the model correctly predicts the frequencies with large components around the first several harmonics of the gear mesh frequency. Measurements do not confirm some of the more detailed features predicted by the model. Some features in the spectra from the numerically derived model can be used to separate the model data with and without planted faults. These features were not found useful for detecting faults in the vibration measurements of real gearboxes in flight due to added complexity in the spectra from real gearboxes.
Vibration Processing Techniques for Fault Detection in Gearboxes
Authors: Wilk Andrzej B. , Madej Henryk M. , Łazarz Bogusław E.
Published: June 2008

Vibration analysis is a very important tool in condition monitoring of operating machines. Many signal processing methods have been developed to extract information about incipient faults from externally measured vibration signals. The article presents the laboratory examinations of some faults in spur and helical gears. In case of spur gears two types of progressing local faults of cracked and chipped gear tooth were simulated and the smoothed pseudo Wigner-Ville distribution was used to demonstrate fault advancement via residual vibration signal analysis. Observing changes in the features of the WV distribution in the contour plots and changes of Kurtosis value monitored the progression of a fault. In case of helical gears some signal changes of transverse vibration velocity of shafts during the process of pitting growth in the tooth working surface have been investigated. Some new indices of pitting wear have been suggested and compared with other non-dimensional discriminants.
Enhanced Approach for Application of Longitudinal Plunging in Manufacturing of Spur Gear Drives
Authors: Zanzi Claudio , Pedrero Jose´ I.
Published: June 2008

This paper represents an enhanced approach for application of longitudinal plunging in the manufacturing process of spur gear drives in order to localize the bearing contact. The proposed approach is based on application of a grinding disk performing a planar curvilinear trajectory. The main innovation is the tilt of the plane containing the curvilinear trajectory performed by the center of the grinding disk. The proposed manufacturing process allows the following improvements to be obtained: (i) uniform length of the major axes of the instantaneous contact ellipses all over the path of contact, (ii) reduced sensitivity of the shift of the path of contact to errors of alignment, and (iii) reduced level of contact and bending stresses. Numerical examples of design are represented.