The changing landscape of hydraulic drives is leading many fluid power specialists to quickly adapt to using variable speed pump drives. Optimum utilization of these drives requires, in many cases, additional system design considerations.

EDITORS’ NOTE: “The Applications of Bevel Gears” is the excerpted third chapter of Dr. Hermann Stadtfeld’s latest book — Gleason Bevel Gear Technology (The Gleason Works, Rochester, New York, USA; All rights reserved. 2014; ISBN 978-0-615-96492-8.), which appears here unabridged through the kind graces of Dr. Stadtfeld and Gleason Corp. Future installments will appear exclusively in Power Transmission Engineering and Gear Technology magazine over the next 12 to 18 months.

Four types of gear devices with great transmission ratios (simply called great ratio gears or GRGs) are discussed in this paper. They are strain wave gearing devices (SWGs), trochoidal gear reducers (TGRs), hypocyclic gear reducers (HGRs) and James Ferguson-type planetary drives (JFDs). The structures, advantages and basic performances of these four devices are compared. The latest design and strength analysis methods are also introduced. To conclude, the future tendencies of GRGs are predicted.

Believe me when I tell you that — as a domestic automotive engineer — I bleed U.S. manufacturing. I have never lived more than 50 miles from Detroit,

Wind turbine gearboxes are subjected to a wide variety of operating conditions, some of which may push the bearings beyond their limits. Damage may be done to the bearings, resulting in a specific premature failure mode known as white etching cracks (WEC), sometimes called brittle, short-life, early, abnormal or white structured flaking (WSF). Measures to make the bearings more robust in these operating conditions are discussed in this article.

Varying installation requirements for worm gears, as, for example, when used in modular gear systems, can necessitate grease lubrication - especially when adequate sealing for oil lubrication would be too complex. Such worm gears are being increasingly used in outside applications such as solar power plants and slew drives. While knowledge about the operating conditions is often appropriate, the basic understanding for load capacity and efficiency under grease lubrication is quite poor. Investigations done at FZG and sponsored by FVA/AiF are shown here to give an impression of the basic factors of load capacity and efficiency. The results of the investigation indicate a satisfying quality of calculations on heat, load capacity and efficiency based on characteristic parameters of the base oil with only slight modifications to the methodology known from DIN 3996 or ISO TR 14521.

The growth of worldwide energy consumption and emerging industrial markets demands an increase of renewable energy shares. The price pressure coming from coal, oil, nuclear and natural gas energy - combined with enormous worldwide production capacities for components of wind turbines - make wind energy a highly competitive market. The testing and validation of gearboxes within the test rig and the turbine environment attract a strong focus to the needs of the industry. The following contribution sums up the typical process requirements and provides examples for successful system and component verifications based on field measurements.

Beginning with a brief summary and update of the latest advances in the calculation methods for worm gears, the author then presents the detailed approach to worm gear geometry found in the revised ISO TR 10828. With that information, and by presenting examples, these new methods are explained, as are their possibilities for addressing the geometrical particularities of worm gears and their impact upon the behavior and load capacity of a gearset under working conditions based on ISO TR 14521 — Methods B and C. The author also highlights the new possibilities offered on that basis for the further evolution of load capacity calculation of a worm gearset based on load and contact pressure distribution.

There are three major types of reluctance motors: all three reluctance motors are non-permanent magnet, brushless motors. They are synchronous motors with a non-linear relationship between torque and current. The variable-reluctance step and switched-reluctance motors utilize the principle of magnetic attraction by inducing magnet poles within the soft-iron rotor, and by energizing a set of coils wound around stator teeth resident in the laminated stator. These two reluctance motors must be sequentially excited to achieve continuous, steady-state rotation. The design of all reluctance motors requires finite element analysis (FEA) software.

Many of us have been there; the bearings had the correct preload. You know it, you were there, and you personally saw the measurements. Now, the testing is done and the preload is gone. Not a little gone, not sort of gone - gone, gone. Finger pointing ensues. Suppliers are dragged in by their wrinkly Polo collars. You know the drill. Losing preload in a tapered roller bearing (TRB) system over the life of your application can be a troublesome problem, particularly for gear sets that are prone to noise or severe applications that rely on a very rigid and stable system.