Considerations in the Design of Primary Worm-gear Drives for Astronomical Telescopes

1969 ◽  
Vol 1 (5) ◽  
pp. 245-247
Author(s):  
D. G. S. Groeneveld
Keyword(s):  
Power Transmission ◽  
Design Methods ◽  
Worm Gear ◽  
Standard Design ◽  
Gear Drives

Worm-gear drives for astronomical telescopes have associated with them certain requirements which cannot be effectively dealt with by applying standard design methods and parameters, since these drives differ in many ways from conventional power transmission gearing.

Geometrical design of skew conical involute gear drives in approximate line contact

2009 ◽  
Vol 223 (9) ◽  
pp. 2201-2211 ◽  
Author(s):  
S H Wu ◽  
S J Tsai
Keyword(s):  
Power Transmission ◽  
Design Approach ◽  
Line Contact ◽  
Contact Sensitivity ◽  
Axis Ratio ◽  
Edge Contact ◽  
Involute Gear ◽  
Surface Durability ◽  
Gear Drives ◽  
Conical Gear

A novel design for skew conical involute gear drives in approximate line contact is proposed. Such a drive has a contact ellipse with a large major-to-minor-axis ratio, which allows it to overcome the weakness of conical gear drives for application in power transmission. This gearing design approach is characterized by reduced edge contact sensitivity and increased surface durability. The edge contact sensitivity that can arise with this kind of gear drive due to assembly or manufacturing errors is evaluated by analysing the value of the shift of the line of action caused by such errors. The surface durability is evaluated by calculating the Hertz stress. Some guidelines are developed based on the analysis of the influence of the gearing parameters on the edge contact sensitivity and the surface durability made possible using this design approach for conical gear drives in the approximate line contact. The guidelines are summarized and, finally, a practical example is given to demonstrate the feasibility of the approximate line contact design.

Subsea Cable Stability on Rocky Seabeds: Comparison of Field Observations Against Conventional and Novel Design Methods

2018 ◽  
Author(s):  
Terry Griffiths ◽  
Scott Draper ◽  
Liang Cheng ◽  
Feifei Tong ◽  
Antonino Fogliani ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Power Transmission ◽  
Small Diameter ◽  
Oil And Gas Industry ◽  
Operational Reliability ◽  
Design Methods ◽  
Gas Industry ◽  
Integrity Management ◽  
Tidal Stream ◽  
Almost All

As offshore renewable energy projects progress from concept demonstration to commercial-scale developments there is a need for improved approaches beyond conventional cable engineering design methods that have evolved from larger diameter pipelines for the oil and gas industry. New approaches are needed to capture the relevant physics for small diameter cables on rocky seabeds to reduce the costs and risks of power transmission and increase operational reliability. This paper reports on subsea cables that MeyGen installed for Phase 1a of the Pentland Firth Inner Sound tidal stream energy project. These cables are located on rocky seabeds in an area where severe metocean conditions occur. ROV field observation of these cables shows them to be stable on the seabed with little or no movement occurring over almost all of the cable routes, despite conventional engineering methods predicting significant dynamic movement. We cite recent research undertaken by the University of Western Australia (UWA) to more accurately assess the hydrodynamic forces and geotechnical interaction of cables on rocky seabeds. We quantify the conformity between the cables and the undulating rocky seabed, and the distributions of cable-seabed contact and spanning via simulations of the centimetric-scale seabed bathymetry. This analysis leads to calculated profiles of lift, drag and seabed friction along the cable, which show that all of these load and reaction components are modelled in an over-conservative way by conventional pipeline engineering techniques. Overall, our analysis highlights that current cable stability design can be unnecessarily conservative on rocky seabeds. Our work foreshadows a new design approach that offers more efficient cable design to reduce project capex and enhance through-life integrity management.

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.

Computerized Design, Generation and Simulation of Meshing and Contact of Modified Flender Worm-Gear Drives

1996 ◽  
Author(s):  
I. H. Seol ◽  
Faydor L. Litvin
Keyword(s):  
Gear Tooth ◽  
Worm Gear ◽  
Numerical Examples ◽  
Transmission Errors ◽  
Gear Drive ◽  
Bearing Contact ◽  
Tooth Surfaces ◽  
Design Generation ◽  
Computerized Simulation ◽  
Gear Drives

Abstract The worm and worm-gear tooth surfaces of existing design of Flender gear drive are in line contact at every instant and the gear drive is very sensitive to misalignment. Errors of alignment cause the shift of the bearing contact and transmission errors. The authors propose : (1) Methods for computerized simulation of meshing and contact of misaligned worm-gear drives of existing design (2) Methods of modification of geometry of worm-gear drives that enable to localize and stabilize the bearing contact and reduce the sensitivity of drives to misalignment (3) Methods for computerized simulation of meshing and contact of worm-gear drives with modified geometry The proposed approach was applied as well for the involute (David Brown) and Klingelnberg type of worm-gear drives. Numerical examples that illustrate the developed theory are provided.

The Production of Small Worm Gears for Experimental Work

1947 ◽  
Vol 156 (1) ◽  
pp. 368-372
Author(s):  
A. M. Gunner
Keyword(s):  
Experimental Work ◽  
Research Laboratory ◽  
Single Point ◽  
General Rule ◽  
Worm Gear ◽  
Pressure Angle ◽  
Worm Wheel ◽  
Worm Gears ◽  
Shaft Angle ◽  
Gear Drives

Small worm gear drives are a common feature in the design of many types of apparatus, and the following description of the methods used for producing them in an experimental establishment may be of interest. Quantities are small, one or two to each pattern being the general rule, but there is certainly no lack of variety. The worms and wheels most often called for range in size up to 1½ inches and 6 inches diameter respectively, while pitches vary from 10 to 60 d.p. (diametral pitch). Addendum and dedendum proportions of 1/ PN and 1·25/ PN have been standardized, and a pressure angle of 20 deg. is adopted throughout. The gears are designed as hollow-faced helical (spiral) gears, and all calculations are based on the normal pitch. This is to enable standard hobs and cutters to be used for the worms. The shaft angle is usually 90 deg., but the angle of crossing may be varied up to 10 deg. either way on the particular machine employed for cutting the wheels. For many applications, backlash must be reduced to the very minimum consistent with smooth running; and to avoid the extreme accuracy of workmanship which an exact centre distance would necessitate, provision is usually made for adjustment of the worm. Although the Reinecker tangential feed method of worm wheel generation by a single-point tool —representing one tooth of a hob—is generally known, very little information on cutter forming is available. The method outlined was developed at the Admiralty Research Laboratory. Given the use of a modern worm grinder (not available), it should be possible to profile-relief grind these cutters after hardening.

Contact Characteristics of Recess Action Worm Gear Drives With Double-Depth Teeth

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Wei-Liang Chen ◽  
Chung-Biau Tsay
Keyword(s):  
Worm Gear ◽  
Surface Topology ◽  
Design Parameters ◽  
Kinematic Error ◽  
Contact Ratio ◽  
Tooth Contact Analysis ◽  
Gear Drive ◽  
Contact Patterns ◽  
Bearing Contact ◽  
Gear Drives

Based on the previously developed mathematical model of a series of recess action (RA) worm gear drive (i.e., semi RA, full RA, and standard proportional tooth types) with double-depth teeth, the tooth contact analysis (TCA) technique is utilized to investigate the kinematic error (KE), contact ratio (CR), average contact ratio (ACR), instantaneous contact teeth (ICT) under different assembly conditions. Besides, the bearing contact and contact ellipse are studied by applying the surface topology method. Three numerical examples are presented to demonstrate the influence of the assembly errors and design parameters of the RA worm gear drive on the KE, CR, ACR, ICT, and contact patterns.

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