Mechanism crankshaft

The reciprocating motion of the piston is transformed into rotaiy motion on the crankshaft by two of the links in the slider-crank mechanism—the connecting rod and the crank (hidden from view in this cross section). The connecting rod joins the piston pin to the crank pin. The crank connects the crank... 

The four-stroke and two-stroke engines described above both use the slider-crank mechanism to transform piston work into crankshaft torque, but other intermittent-combustion engines have been conceived that use different kinematic arrangements to achieve this end. The only one that has realized significant commercial success is the rotary engine first demonstrated successfully in Germany by Felix Wankel in 1957. 

Single Acting Compression of gas takes place only in one end of the cylinder. This is usually the head end (outboard end), but may be the crank end (inboard end or end of cylinder nearest crankshaft of driving mechanism). See Figures 12-2A, 12-3A, and 12-4A. 

In the compression ignition cycle, the air is compressed and the fuel is injected into the compressed air at a temperature sufficiently high to spontaneously ignite the fuel. The heat released is converted to mechanical work by expansion within each cylinder and, by means of the reciprocating motion of the piston, is converted to rotary motion at the crankshaft. 

Fig. 4a-c. Sketch of simple motional mechanisms and resulting averaged field gradient tensors a Kink-3-bond motion b crankshaft-5-bond motion c 180° jump of phenyl ring... 

Dyn ic mechanical analysis was discussed in terms of the nodular morphology concept in crossllnked structures. Beta relaxations in all the cured resins were bimodal in appearance. But, vAiile MPD-cured resins shewed a maximum at 25 C with a smaller shoulder at -40 C, TDA and DAEB-cured resins had maxima at -40 C with a less significant peak at 25 C. For DAIPB and DATBB-cured resins the two peaks were approximately equal in magnitude. The two overlapping peaks at -40 and 25 C were attributed to crankshaft motions in the matrix and nodules. 

The mechanical aspect of these balances typically employs a crankshaft or rocker arm assembly that supports the weights. The weights are engaged or disengaged on the balance beam as the shaft is turned. Typically, only four weights per... 

The mechanical dispersion peaks in low-Tg epoxies such as Bisphenol-A based resin (Epon 828, products from Shell Development Company) have been the subject of numerous studies 143,145148,152 "155, l59>. The alpha-dispersion peak related to the glass transition can undoubtly be attributed to the large-scale cooperative segmental motion of the macromolecules. The eta-relaxation near —55 °C, however, has been the subject of much controversy 146,153). One postulated origin of the dispersion peak is the crankshaft mechanism at the junction point of the network epoxies (Fig. 17). The crankshaft motion for linear macromolecules was first propos-ed 163 166> as the molecular origin for secondary relaxations which involved restricted motion of the main chain requiring at least 5 and as many as 7 bonds 167>. This kind of... 

Fig. 3.9 Diagrams of molecular relaxation mechanisms (a) conformational flip of chlorohexane, (b) crankshaft rotation in polyethylene.

Fig. 2 The crankshaft mechanism is a simple way of considering the motions of a polymer chain permitted by increases in free volume. The molecule is visualized as a series of balls and rods, and these move as the free volume increases. (View this art in color at www.dekker.com.)...

Fig. 1 Free volume, v, in polymers (A) the relationship of free volume to transitions, and (B) a schematic example of free volume and the crankshaft model. Below the Tg in (A) various paths with different free volumes exist depending on heat history and processing of the polymer, where the path with the least free volume is the most relaxed. (B) shows the various motions of a polymer chain. Unless enough free volume exists, the motions cannot occur. (From Menard K. Dynamic Mechanical Analysis A Practical Introduction, CRC Press Boca Raton, 1999).

This movement of the pistons turns the crankshaft, which, through a series of mechanical connections, turns the wheels of the car. 

First is the crankshaft mechanism of Schatzki.16 It has been observed for many polymers containing linear (CH2) sequences with n = 4 or greater, that a secondary relaxation occurs at about -120 °C at 1 Hz. This seems to be true regardless of whether the CH2 sequences occur in the main chain or in the side groups. Thus both polyethylene and poly-n-butyl methacrylate exhibit this relaxation. The mechanism proposed by Schatzki is shown in Figure 5-14. 

The motion responsible for the relaxation is a rotation about the two co-linear bonds 1 and 7 such that the carbon atoms between bonds 1 and 7 move in the manner of a crankshaft. The co-linearity of the two terminal bonds is achievable if there are four intervening carbon atoms on the assumption of tetrahedral valence angles and a rotational isomeric state model. Support is to be found for the crankshaft mechanism in the fact that the activation energy estimated for the model, 54 kJ/mol, is close to the experimental results, 50-63 kJ/mol, and in the fact that the predicted free volume of activation, about four times the molar volume of a CH2 unit, is also in good agreement with experimental estimates based on pressure studies. 

In our institute we have developed a simple reciprocating piston engine by omitting mechanically operated control valves. In Fig. 1 a cross section of this new engine is shown. The cylinder (1) is mounted on a stainless steel tube (3) which is connected with the driving gear operating at room temperature. The piston (2), shown in its upper end position, is flexibly connected to the piston rod (4), which also consists of a stainless steel tube and works on a simple crankshaft. The upper end of the piston rod is constrained to move in the vertical direction in order to avoid lateral forces on the piston. 

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