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Epicyclic gearboxes
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
In a simple band brake the band wraps partly around a rotating drum and a braking action is obtained by pulling the band tightly on to it, the actual braking force being equal to the difference in tensions at the two ends of the band. The band brake was a natural choice for the designers of early epicyclic gearboxes, because the annulus gear lent itself to a convenient form of drum construction against which the band could be contracted. However, a band brake can be a fickle device and many early troubles were caused by chattering and grabbing of the bands. It was Major W.G. Wilson (Section 16.1) who later recognized the need for more attention to detail in brake band design, including the fully floating principle of band application that is found in modern automatic gearboxes.
Anchor operations and deployment
Published in D.J. House, Ship Handling, 2007
In the event that unrestricted descent of the anchor is allowed to take place, i.e. letting go, then damage to the windlass gearing and/or motors may be unavoidable. Speed limiting devices operating on the band brake may make the operator's task of control easier but overheating could still become a problem with subsequent loss of braking efficiency. As such, over reliance on a restrictive speed, system should not become the order of the day, and the principle of walking the anchor back all the way should be adhered to.
An efficient motion generation method for redundant humanoid robot arms based on motion continuity
Published in Advanced Robotics, 2018
Meng Li, Weizhong Guo, Rongfu Lin, Changzhen Wu
In this section, an example arm motion was presented to test the availability and practicability of the proposed motion generation method. The preplanned hand trajectory is shown in Figure 19. For illuminating the intrinsic motion rules that the arm motion automatically follows the hand motion, no optimization algorithm is added. Since the sampled motion does not include any obstacle, the arm motion is generated based on the procedure given in Section 3.1. The generated arm motion corresponding to the planned trajectory is shown in Figure 20. Figure 21 provides the details of the automatically generated wrist trajectory and elbow trajectory. According to the features of the hand trajectory, the rules automatically generated an ellipse-like enclosed elbow trajectory. From the arm motions in Figures 20 and 21, it can be seen that the arm motion is continuous and smooth during the movement. Figure 22 is the motors’ torques, velocities and accelerations during the movement, respectively. The curves in Figure 22 show that motors’ motion is very smooth during the movement. However, as shown in Figure 23 because of the gravity acceleration and band brake of the motor, jerk and volatility remains in the startup process.