Spragging

During the period of mining, the roof management below the inner interlocked tail roadway is also very important, pulling supports must be in time or in advance, supports must be tightened, and the face sprag must be reinforced. Besides that... 

Mechanical assembly methods are widely used, but there is always a risk of high local stresses. Moulded-in inserts are generally better than selftapping screws in the more demanding applications. Sprags and staples are used very successfully with tough plastics. 

India is the major producer of sandalwood oil (East Indian sandalwood oil). A closely related oil, Australian sandalwood oil, is derived from the wood of Eucarya spicata sprag. 

Locos and rolling stock left parked on the main haulage without stop blocks or chain sprags etc. This was even the case where tracks were on the downgrade toward the tip. 

The cab should include a deadman s pedal sited to rttake it easy to use (thereby obviating the temptation to defeat it by spragging). Operation of the loco should be impossible unless the deadman s pedal in both the driver and guard cabs are depressed. 

This is a mechanical means of locking the wheels on locomotive wagons when not in use. There are a wide range of devices used from simple metal bars to specifically designed devices (such as aeroplane sprags). 

In Sects. 4.3.1 and 4.3.2, we study the classic Painleve s example and derive the conditions for the occurrence of the paradoxes. In Sect. 4.3.3, the concept of self-locking is introduced which is closely related to the kinematic constraint instability mechanism. In the rigid body systems, this phenomenon is sometimes known as jamming or wedging [97]. As we will see later on, the self-locking is an important aspect of the study of the dynamics of the lead screws. In Sect. 4.3.4, a simple model of a vibratory system is analyzed where the kinematic constraint mechanism leads to instability. In the study of disc brake systems, similar instability mechanism is sometimes referred to as sprag-slip vibration [7]. Some further references are given in Sect. 3.3.5. 

From (4.50), it is evident that if 0 tan (1/pj ), then N oo and further motion becomes impossible. In a more realistic setting where some flexibility is assumed, the motion continues by the deflection of the parts (see, e.g., Hoffmann and Gaul [98]). After sufficient deformation of the contacting bodies, slippage occurs which allows the bodies to assume their original configuration and the cycle continues. This situation is sometimes known as the sprag-slip limit cycle. 

Fig. 4.20 Simple model to demonstrate sprag-slip vibration...

Hoffinaim N, Gaul L (2004) A sufficient criterion for the onset of sprag-slip oscillations. Arch Appl Mech 73 650-660... 

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