A plunger pump having improved durability without leading to a reduction in productivity is provided. A pump apparatus includes a sliding portion provided between a stopper portion and an eccentric cam in a direction of an eccentric central axis and having a lower frictional coefficient between the sliding portion and the eccentric cam than a frictional coefficient between the stopper portion and the eccentric cam.

A plunger pump having improved durability without leading to a reduction in productivity is provided. A pump apparatus includes a sliding portion provided between a stopper portion and an eccentric cam in a direction of an eccentric central axis and having a lower frictional coefficient between the sliding portion and the eccentric cam than a frictional coefficient between the stopper portion and the eccentric cam.

An internal combustion engine includes a crankshaft and at least one piston coupled to the crankshaft for executing strokes in a cylinder as a result of rotation of the crankshaft. An eccentric shaft is coupled to the crankshaft and to the piston in such a way that strokes of the piston are adjusted by the eccentric shaft. A phase adjuster adjusts a phase of the coupling of the eccentric shaft to the crankshaft.

The arrangement of the present invention is applied to a compressor which comprises a bearing hub housing a crankshaft and presenting at least a first and a second bearing portion, spaced apart by a circumferential recess. The crankshaft presents at least a first and a second support portion, spaced apart by a circumferential recess, which is offset from the circumferential recess of the bearing hub. At least one of the bearing portions and support portions has an axial extension superior to that required for radially bearing the crankshaft, the first and second bearing portions defining, with the first and second support portions, respectively, a first and a second radial bearing regions having the axial extensions required for a radial bearing for the crankshaft, presenting lower loss by viscous friction.

The arrangement of the present invention is applied to a compressor which comprises a bearing hub housing a crankshaft and presenting at least a first and a second bearing portion, spaced apart by a circumferential recess. The crankshaft presents at least a first and a second support portion, spaced apart by a circumferential recess, which is offset from the circumferential recess of the bearing hub. At least one of the bearing portions and support portions has an axial extension superior to that required for radially bearing the crankshaft, the first and second bearing portions defining, with the first and second support portions, respectively, a first and a second radial bearing regions having the axial extensions required for a radial bearing for the crankshaft, presenting lower loss by viscous friction.

A balance shaft for balancing forces of inertia and/or moments of inertia of a reciprocating-piston internal combustion engine, including: at least one elongate main body; at least one bearing seat, disposed on the elongate main body for the mounting of a radial bearing. In the center point of the bearing seat there is provided the rotational axis of the balance shaft. The elongate main body may be formed of an integral tubular element, and the center of mass of the elongate main body may lie outside the rotational axis of the balance shaft.

A balance shaft for balancing forces of inertia and/or moments of inertia of a reciprocating-piston internal combustion engine, including: at least one elongate main body; at least one bearing seat, disposed on the elongate main body for the mounting of a radial bearing. In the center point of the bearing seat there is provided the rotational axis of the balance shaft. The elongate main body may be formed of an integral tubular element, and the center of mass of the elongate main body may lie outside the rotational axis of the balance shaft.

An eccentric shaft (1) for a compaction machine comprising at least one pair of straight circular cylindrical bearing seats (2,3) arranged on either side of a center of gravity (TP) of the eccentric shaft (1). The bearing seats (2,3) are arranged such that cylinder axes (4, 5) thereof approximately intersect or cross each other at a concave angle (V), less than 179.8 degrees, towards the center of gravity (TP) when the eccentric shaft (1) is at rest.

An eccentric shaft (1) for a compaction machine comprising at least one pair of straight circular cylindrical bearing seats (2,3) arranged on either side of a center of gravity (TP) of the eccentric shaft (1). The bearing seats (2,3) are arranged such that cylinder axes (4, 5) thereof approximately intersect or cross each other at a concave angle (V), less than 179.8 degrees, towards the center of gravity (TP) when the eccentric shaft (1) is at rest.

Vibratory device (1) for compacting machine comprising a shaft (3), at least one eccentric mass (4,5,6) rotatable arranged around the shaft (3) and at least one motor (8) arranged around the shaft (3). The motor (8) is arranged for rotating drive of at least one of the eccentric masses (4,5,6) around the shaft (3). The motor (8) comprise a winding unit (9) connected to, the shaft (3) and a rotor (10) rotatable arranged around the shaft (3) and connected to at least one of the eccentric masses (4,5,6). The rotor (10) is arranged to be actuated by at least one magnetic field to rotation around the shaft (3) and the winding unit (9) is arranged to generate the magnetic fields which actuates the rotor (10) to rotation.