Ratchets

Peskin C S, Odell G M and Oster G F 1993 Cellular motions and thermal fluctuations the Brownian ratchet Biophys. J. 65 316... 

Manually adjusted screw or ratchet take-ups that adjust the position of the tail pulley to control belt tension can be used on relatively short, light duty conveyors. Automatic take-ups are used on conveyors over about 25 to 30 m long. The most common is the weighted automatic gravity take-up (see Fig. la). Other types of automatic take-ups have hydrauHc or pneumatic powered devices to adjust a snub pulley position and maintain a constant belt tension. The requited take-up movement varies according to the characteristics of the belt constmction and the belt length. Typically, take-up movements for pHed belts are 2% to 3% of the center distance between head and tail pulley, and about 0.5% for steel cable belts. The take-up movements requited for soHd woven belts are usually shorter because of the lower elastic stretch. Take-up requirements for a particular situation should be confirmed by the belt manufacturer. 

Auxiliary Equipment Elevating conveyors must be equipped with some form of holdback or brake to prevent reversal of travel and subsequent jamming when power is unexpectedly cut off. Ratchet and wedge roUer-type holdbacks are commonly used. Solenoid brakes and spring clutches may also be employed. 

When the motor is started, the pins are lifted up by the ratchet base and are held in the ratchet cover due to centritugal force thus releasing the ratchet for rotation... 

Fig. 1.2. A close-up of the mechanical lubricator on the traction engine. Unless the bore of the steam cylinder is kept oiled it will become worn and scored. The lubricator pumps small metered quantities of steam oil into the cylinder to stop this happening. The drive is token from the piston rod by the ratchet and pawl arrangement.

Below a temperature of Toi 260 K, the Ceo molecules completely lose two of their three degrees of rotational freedom, and the residual degree of freedom is a ratcheting rotational motion for each of the four molecules within the unit cell about a different (111) axis [43, 45, 46, 47]. The structure of solid Ceo below Tqi becomes simple cubic (space group Tji or PaS) with a lattice constant ao = 14.17A and four Ceo molecules per unit cell, as the four oriented molecules within the fee structure become inequivalent [see Fig. 2(a)] [43, 45]. Supporting evidence for the phase transition at Tqi 260 K is... 

Gespenstf n. specter, ghost, phantom. Gesperr(e), n. locking device, catch, ratchet, gespieen, p.p. (of speien) spat vomited. Gespinst, n. spun yarn spun goods thread (textile) fabric web cocoon, -faser, /. textile fiber, -pflanze,/. textile plant fiber plant. 

Sperr-klmke, /. catch, pawl, ratchet, detent, -kreis, m. block circuit, wave trap circuit, -metail, n. ply metal, -rad, n. ratchet wheel, cog wheel, -schichtenzelle, /. solid photovoltaic cell, -ung, /. shutting, etc. (see sperren). -ventil, n. stop valve, check valve, shut-off valve, -waffe, /. defensive weapon, -wasser, n. sealing water. 

Kerosene lamps have a flat cloth wick. Flame height is determined by the height of the wick, which is controlled by a ratchet knob. A glass chimney ensures both safety and a stable, draft-free flame. 

The most familiar examples of one-way clutches are the bicycle freewheel, which enables the cyclist to stop pedaling without stopping the bicycle, and the non-reversing ratchet used on vertical turbine pumps. 

The ease and economy of manufacturing gears, cams, bearings, slides, ratchets, and so on with injection-moldable TPs have... 

Figure 4. The Brownian ratchet model of lamellar protrusion (Peskin et al., 1993). According to this hypothesis, the distance between the plasma membrane (PM) and the filament end fluctuates randomly. At a point in time when the PM is most distant from the filament end, a new monomer is able to add on. Consequently, the PM is no longer able to return to its former position since the filament is now longer. The filament cannot be pushed backwards by the returning PM as it is locked into the mass of the cell cortex by actin binding proteins. In this way, the PM is permitted to diffuse only in an outward direction. The maximum force which a single filament can exert (the stalling force) is related to the thermal energy of the actin monomer by kinetic theory according to the following equation ...

When a droplet is deformed asymmetrically, the ratchet motions of the droplet can be induced as demonstrated on the vibrated gradient surface and on a saw-shaped electrode on which the wetting was changed by electrowetting [48]. 

We showed that the ratchet motions of a droplet were induced by very simple asymmetric guides [45]. Figure 16.7 shows a schematic drawing of the electrode causing the ratchet motions of a droplet. 

Ratchet Motion of a Droplet Caused by Dynamic Motions of the Wetting Boundary... 

The ratchet motion of a droplet was induced by electrochemical control of the wetting distributions on the surface [44]. Figure 16.9 shows the principles for the generation... 

An electric field-induced bending of gel makes a worm-like motion feasible [18]. A weakly crosslinked PAMPS gel in a surfactant solution bends toward the anode under dc electric fields. Both ends of the gel are placed on front and rear hooks and are then hung on a plastic ratchet bar. When a varying electric field of 10 V/cm and 0.5 Hz is applied, the gel moves forward in the solution with a bending motion at a velocity of 25 cm/min. 

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