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Oil-Hydraulic Pressure Pumps

It is possible without any difficulties to also employ oil as the transmission medium in the water-hydraulic pumps described in the previous chapter. The expenditure involved for these pumps would, however, be out of all proportion, as oil-hydraulic pumps are of much simpler and cheaper design, as there is no need to provide for stuffing boxes and separate systems for water and lubricating oil. Pump valves may also be omitted, if the cylinder bores are made to rotate over a cam plate. [Pg.207]

There are two types of oil-hydraulic pumps, viz. constant delivery and variable delivery pumps. The output of the latter is controlled by varying the stroke of the piston. The piston stroke chosen is very short as compared with water pumps, thus rendering possible a considerable increase in motor speed and to couple the pumps directly with the motor (see Fig. 165). This type also permits of using an essentially larger number [Pg.208]

Variable delivery oil-hydraulic pressure pumps are in axial or radial design as illustrated in the schematic representation Fig. 170. The radial pump possesses a stationary shaft a on which the pump body 6, which is. [Pg.209]

This characteristic feature of the pump is of extreme value when the deliveries of two mating bores are merged into one on the outside and hence piped to the respective power- and return sides of the press piston. [Pg.211]

Thus the piston performs an advance and return motion and the control gear normally required with a constant delivery pump, can therefore be omitted. This simple circuit arrangement calls for equal-sized power- and return surfaces of the press piston which also results in equal speed rates in either direction. When these areas are of different size - as it is mostly the case in practice - and idling- and return strokes are to be performed at considerably higher speed rates than the power stroke, it is necessary to provide the press with a filling valve and a check valve. The corresponding circuit diagram is illustrated in Fig. 171. [Pg.211]


Oil-hydraulic pressure pumps are frequently employed for the operation of cable presses instead of pressure water pumps, see p. 203. Their advantage being that they require less floor space and that they may even be mounted on the press. Claims in favor of pressure water pumps are the higher operating pressures, resulting in a simpler design of the press, and, last not least, the elimination of the danger of fire. [Pg.44]

Fig. 167, 168 and 169 show an oil-hydraulic pressure pump the outstanding feature of which being the provision of intake- and delivery valves. This pump has proved itself especially at high pressures of 300 to 400 atmospheres on a continuous duty basis. Valve-less pumps have... [Pg.209]


See other pages where Oil-Hydraulic Pressure Pumps is mentioned: [Pg.207]   


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