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Test results for the trial batch of refractories made of dense magnesite powder in the converter lining in the trunnion zone showed that they are promising for application compared with ordinary dolomite goods with a pitch bond. The average wear of the test refractory is not more than 1.0 mm/heat, while dolomite-pitch shows a wear of 1.5 mm/heat. The resistance of blocks of dense magnesite powder in the lining of steel discharge apertures of a converter also proved to be higher than periclase (83 heats against 69).

The trunnion bearing total hip prosthesis was designed in 1961. Challenging the inevitable phenomenon of wear, a femoral head made of plastic material mated with a femoral component on a trunnion, with a pelvic component in a ball and socket joint, the two peripheral components being made of chromium cobalt alloy (1–8). Wear would be restricted to the interpositum, thus allowing easy replacement, leaving the cemented main components untouched (Fig. 1).

The relation of the occurrence of airframe acoustic emissions to aircraft manoeuvre are reported for Avro CF-100 upper forward wing trunnions. Periods of excessive noise are found when the airframe load is changing during entry to and exit from sustained-G manoeuvres. During constant-G periods, the airframe noise level is reduced by a factor of more than one hundred. These quiet periods provide a suitable signal-to-noise level for the in-flight detection and monitoring of slow, stable crack growth in common airframe materials, even in a noisy load transfer component such as the wing trunnion studied here. Simultaneous in-flight acoustic emission measurements in symmetrically-located airframe components are also reported. The ratio of the number of recorded event counts in a cracked component to that in an uncracked component during the same flight is found to increase linearly with the crack face area for through crack lengths in the range 0–5 mm.

A subcritical liquid hydrogen orbital storage and transfer experiment is being designed for flight in the shuttle cargo bay. The Cryogenic Fluid Management Facility (CFMF) includes a liquid hydrogen storage tank supported in a vacuum jacket by two fiberglass epoxy composite trunnion mounts. The capability of the CFMF to meet a seven mission requirement is extremely sensitive to the fatigue life of the composite trunnions at cryogenic temperatures. An E-glass/S-glass epoxy composite material was selected for the trunnions since it provided desirable strength, weight and thermal characteristics. Because of the limited extent of analytical or experimental treatment of the fatigue life of this composite at cryogenic temperature, an experimental program was conducted to provide verification of the trunnion design and performance capability at ambient and liquid hydrogen temperatures. Basic material fatigue property data were obtained for the laminate of interest using specifically prepared test specimens. Full-scale trunnions were manufactured and subjected to cyclic load testing to verify fatigue life. An analytical evaluation of the thermal performance of the trunnions was conducted, and a test setup is being manufactured to correlate analytical predictions with test results.

Analyse theorique pour une conception pratique des paliers de tourillons de joints universels

Since the beginnings of hip arthroplasty, the concept of a rotating prosthesis has been realized by several authors (1,2,8,11,13,14) mostly with encouraging clinical results (4,7,12). After the first presentation of the Weber-Huggler total hip prosthesis the implantation of this modified rotating prosthesis had been wide-spread in the German-speaking countries until 1973. In the first version of the Weber-Huggler type, a polyester (polyethylene terephtalate = PETP) ball articulating with a cobalt-chromium alloy cup rotated on a trunnion of the femoral stem (13,14).

Source: https://erdc-library.erdc.dren.mil/jspui/ Tests were conducted using a 1:50-scale section model to determine the magnitude and frequency of the hydrodynamic loads acting on the tainter gate trunnions and hoist cables, and the stilling basin apron monoliths, baffles, and end sill. Force measurements at the gate trunnions indicated that the trunnions were subjected to static loadings in an upward and downstream direction. Gate hoist cable loads were occasionally periodic and always in a downward direction. The location, frequency, and magnitude of the resultant forces acting on the stilling basin apron were determined. Also tests were conducted to determine the forces acting on the baffles and end still. The measured drag forces on the baffle blocks were significantly higher than drag forces computed from drag coefficients. This indicated the need for research or site-specific studies to develop design guidance for determining the individual and collective forces acting on stilling basins. Piezometers and electronic pressure cells were used to measure pressure distribution in the stilling basin. Water-surface profiles were obtained along the longitudinal center line of the stilling basin. A skin plate covering the girders on the downstream side of the tainter gate prevented debris from accumulating on the gate. The skin plate did not alter the hydraulic loads on the tainter gate.

The biomechanics are presented of a bushing principle forming the basis for a trunnion bearing prosthesis in total hip replacement. The femoral stem is equipped with a trunnion on to which a cylindrical plastic sleeve is applied. On top of this a metal casing is placed which forms the femoral head. On flexion-extension this remains stationary in the acetabular cup and motion occurs between the trunnion and the cylindrical sleeve. Friction between head and cup is reduced to a minimum, decreasing the risk of loosening. A follow-up study of 61 hips replaced by the trunnion bearing prosthesis was performed 2.5 years postoperatively. Eighty-eight per cent were considerably improved. There was one deep infection and two femoral stem loosenings.

A trunnion shaft supporting the gun carriage was submitted which shattered during the ballistic tests. It was found that the shaft failed because it possessed extremely low impact strength as a result of improper heat treatment of a steel (SAE 6150) having insufficient hardenability for the section (3 1/4 in.) involved. It is recommended that the trunnion shaft be made from a steel having sufficient hardenability for a 3 1/4 in. round and that it be heat treated to a hardness of 34 to 38 Rockwell C. Bolts attaching the turret to the upper race ring were sheared during the ballistic tests. The bolts were made from SAE 4140 steel satisfactory heat treated to a hardness of 31-33 Rockwell C, and it was concluded that the bolts must be made larger if it is expected that they should withstand the stresses resulting from this type of attack. Bolts attaching the commander's cupola to the turret were fractured during the ballistic attack. The bolts were made from SAE 3140 steel satisfactorily heat treated to a hardness of 33 Rockwell C. It was concluded that they should be redesigned if they are expected to withstand the stresses resulting from the ballistic attack to which they were subjected. Additional keywords: U/A Reports.

A metallurgical examination consisting of fracture, hardness, notched bar impact and microscopic tests has been conducted on two sections of cast armor of variable thickness (2 to 3-1/2 in. and 4-1/2 to 9 in.) and a trunnion pin from the gun mount of the Heavy Tank M6A2E1. The 2 to 3-1/2 in. thick section, because of its high hardness (300 BHN) and temper embrittlement, possessed poor shock resistance. The 4-1/2 to 9 in. thick section, heat treated to a hardness of 248-269 BHN, possessed acceptable toughness. The trunnion pins were heat treated to 300 BHN, a hardness which is considered too low for the application. An increase in hardness to 340 BHN can probably be attained with out excessively impairing the toughness and this increase in strength would, no doubt, be sufficient to prevent the distortion which occurred in the subject pins during ballistic tests upon the tank.

A stress analysis was made of the nose gear of the B-36 bomber. The analysis covers the axle, inner and outer cylinder, piston, torque fittings and arms, and cams. The appendix shows the computations for the nose gear loads, loads at points O,O' and O", loads at sections in the fork, torque arm geometry, and loads at the upper and lower bearings, trunnion and drag brace. A table of the minimum margins of safety is included.

The effects of trunnion cant are significant when firing ammunition with muzzle velocities of 2500 fps or lower. This paper presents the conduct and analysis of data resulting from an experiment (conducted at Ft Stewart, Ga., during the period 23 June-4 July 1963) designed to evaluate the effectiveness of a modified reticle and to assist the gunner in compensating for the effects of trunnion cant. The use of ballistics computers that automatically correct for the effects of trunnion cant is the most satisfactory solution. The data presented show that cant is an important source of gunnery error, and that employment of a modified reticle as an interim measure to assist the gunner in compensating for cant results in increased accuracy of fire.

Objectives Mechanical wear and corrosion at the head-stem junction of total hip arthroplasties (THAs) (trunnionosis) have been implicated in their early revision, most commonly in metal-on-metal (MOM) hips. We can isolate the role of the head-stem junction as the predominant source of metal release by investigating non-MOM hips; this can help to identify clinically significant volumes of material loss and corrosion from these surfaces. Methods In this study we examined a series of 94 retrieved metal-on-polyethylene (MOP) hips for evidence of corrosion and material loss at the taper junction using a well published visual grading method and an established roundness-measuring machine protocol. Hips were retrieved from 74 male and 20 female patients with a median age of 57 years (30 to 76) and a median time to revision of 215 months (2 to 324). The reasons for revision were loosening of both the acetabular component and the stem (n = 29), loosening of the acetabular component (n = 58) and infection (n = 7). No adverse tissue reactions were reported by the revision surgeons. Results Evidence of corrosion was observed in 55% of hips. The median Goldberg taper corrosion score was 2 (1 to 4) and the annual rate of material loss at the taper was 0.084 mm3/year (0 to 0.239). The median trunnion corrosion score was 1 (1 to 3). Conclusions We have reported a level of trunnionosis for MOP hips with large-diameter heads that were revised for reasons other than trunnionosis, and therefore may be clinically insignificant. Cite this article: H. S. Hothi, D. Kendoff, C. Lausmann, J. Henckel, T. Gehrke, J. Skinner, A. Hart. Clinically insignificant trunnionosis in large-diameter metal-on-polyethylene total hip arthroplasty. Bone Joint Res 2017;6:52–56. DOI: 10.1302/2046-3758.61.BJR-2016-0150.R2.

Aims The aim of this study was to compare the design of the generic OptiStem XTR femoral stem with the established Exeter femoral stem. Materials and Methods We obtained five boxed, as manufactured, implants of both designs at random (ten in total). Two examiners were blinded to the implant design and independently measured the mass, volume, trunnion surface topography, trunnion roughness, trunnion cone angle, Caput-Collum-Diaphyseal (CCD) angle, femoral offset, stem length, neck length, and the width and roughness of the polished stem shaft using peer-reviewed methods. We then compared the stems using these parameters. Results We found that the OptiStems were lighter (p < 0.001), had a rougher trunnion surface (p < 0.001) with a greater spacing and depth of the machined threads (p < 0.001), had greater trunnion cone angles (p = 0.007), and a smaller radius at the top of the trunnion (p = 0.007). There was no difference in stem volume (p = 0.643), CCD angle (p = 0.788), offset (p = 0.993), neck length (p = 0.344), stem length (p = 0.808), shaft width (p = 0.058 to 0.720) or roughness of the polished surface (p = 0.536). Conclusion This preliminary investigation found that whilst there were similarities between the two designs, the generic OptiStem is different to the branded Exeter design. Cite this article: Bone Joint J 2017;99-B:310–16.

Total hip replacement (THR) is one of the most successful orthopaedic surgeries; however, failures can occur due to adverse reactions to wear debris. Recently, a large number of failures linked to the release of metal particles from the taper junction between femoral head and femoral stem have been reported. One possible reason for this may be design variations such as taper mismatches associated with the taper and trunnion angles. Could a large taper mismatch lead to inappropriate contact mechanics and increase relative micromotion and thus wear? In this study, 3D finite element (FE) models of a commercial THR from a perfectly matched interface to large taper mismatches and a wear algorithm were used to investigate the extent of wear that could occur at this junction and identify the optimum tolerances in order to reduce the wear. A co-ordinate measuring machine (CMM) was used to analyse the wear depth and volumetric wear rate of the tapers of 54 explanted 36 mm diameter Cobalt Chromium femoral heads, which had been in service for 5.1 years in average, to validate the FE analyses. It was found that a large taper mismatch (e.g. 9.12´) results in a high wear rate (2.960 mm3 per million load cycles). Such wear rates can have a major negative effect on the clinical outcomes of these implants. It was also found that even a slight reduction in mismatch significantly reduced the magnitude of the wear rates (0.069 mm3 per million load cycles on average for 6´ taper mismatch). It is recommended that the cone angles of femoral head and femoral trunnion should be manufactured to produce a taper mismatch of less than 6´ at the taper junction.

Up until the present, converter trunnions were not inspected by nondestructive methods either during their manufacture or during service. During the replacement of the roller bearings, we investigated the feasibility of using ultrasonic inspection and conducted a trial inspection of the cylindrical and end surfaces of the trunnion of converter Noo 2. We used a UDM-type flaw detector with normal probes at a frequency of 1.8 mHz. The sensitivity of the instrument was adjusted on a specimen with a 4-mm-diam. control reflector. When we tried to obtain higher degrees of sensitivity, structural noise arose that made it difficult to read the oscillogram. When an inspection was carried out at 2.5 mHz~ the bottom signal was lacking due to substantial damping and scattering of the ultrasonic waves in the body of the trunnion.

The history of the artificial wrist joint is brief and begins as recently as 1971. The prosthesis is designed as a ball-and-socket joint. The metallic trunnion component is cemented into the radius and the metallic cup component into the carpal and metacarpal II and III bones. There is a central articulating polyethylene ball. The surgical technique itself requires only a few special instruments. The centering of the prosthesis is of utmost importance and requires great care. The fixation stems of the prosthesis can and must be bent and adapted to the skeletal conditions of the individual. The wrist joint prosthesis is indicated for the treatment of severe painful wrist joint destruction--mainly rheumatoid arthritis or degenerative osteoarthritis--in patients not concerned with heavy manual work. Clinical experience over a period of 8 years with 41 wrist arthroplasties has shown that although initially technical errors resulted in a number of re-operations, in almost all cases, however, the final outcome was satisfactory. When necessary, a change of prosthesis or a subsequent arthrodesis of the wrist was always possible.

IN NATURE of September 15 a letter from Prof. A. F. C. Pollard points out that the cylindrical bearings adopted for the vertical axis of the Wild precision theodolite leads to a systematic error of the “order of two to four seconds” in the horizontal angles. We, in Egypt, have not had much experience with theodolites of the Wild design, but we have found that the substitution of cylindrical for the old Y-bearings for the telescope (trunnion) axis of English theodolites has not been found to be an improvement but very much the reverse. Whilst the instrument is new, the errors arising from this fault in design do not obtrude themselves, but as soon as the bearings become worn or one of the standards gets slightly bent, the telescope comes to rest in a different position every time it is raised or lowered in elevation. The error arising from this defect is of an accidental nature and may, in an extreme case, amount to one minute.