It is common in an internal-combustion engine for the piston with rings to move down during the power stroke under the influence of gas pressure. At the same time the piston pushes a connecting rod and thus rotates the crankshaft. Because the connecting rod is connected to the piston and crankshaft by cylindrical hinges, reacting force affects the piston at the angle equal to the angle at which the connecting rod is positioned in the direction of the piston movement while the connecting rod transfers power to the crankshaft. As a result there is a lateral component of reacting force vector. Due to this the piston is pushed to the wall of the cylinder, causing additional frictional force that in turn causes power losses, especially at high working loads. Besides, it hastens the wear-out of the cylinder-piston pair.

In the presented Engine a slider is included below the piston and is connected to the piston by an auxiliary connecting rod (AC-rod). Moving coaxially with the piston, the slider sets in motion the crankshaft with the aid of a connecting rod.

In the picture, Figure 1 is a fragment of Engine that is a V-engine, cut off by a transversal plane going through two end cylinders. Here AC-rod 7 is connected pivotally by its ends with a piston pin and slider 9.

Piston 4 with the aid of AC-rod 7 sets into motion slider 9 which has two needle bearings 8 at its ends and these bearings roll easily along the side square shoot planes of the guides. One of the guides is guide 2. The other end of the slider abuts and rolls on the square shoot of the duplex guide that is installed in the middle part of the cylinder block and is absent on this fragment of Engine. Since a slider takes up the lateral component of the force, the needle bearing during this stroke is pressed against one of two parallel opposite side planes 2(a) of the guide’s square shoot. At the same time the other, opposite, side plane does not abut with the needle bearing. When in the next stroke the lateral component of the force changes its direction into the opposite one, the needle bearing is pressed against the other side plane. Thus, during each stroke a clearance between a needle bearing and side planes of the guide is taken up. This clearance corresponds to the running fit (or easy fit). Such clearance is sufficient for the needle bearing to abut and slide on one of the planes without touching the other one. At the same time such clearance practically doesn’t involve lateral displacement of a slider and, consequently, doesn’t create lateral loads on the piston.

Here also: 1-cylinder block, 1(b) and 1(d)-guide fastening bores, 5-crankshaft, 6 – connecting rod, 10-bolts, 12-bronze L-plate inserted into the square shoot, butting against the frontal plane 2(b).