Fig. 2379.
A method of overcoming this defect is shown in [Fig. 2379], where the joint faces are left open, and four set-screws s, s, two on each side of the rod, pass through the flange of one brass and abut against the face of the other, serving to adjust the fit of the brasses to the journal, and lock them in their adjusted position, locking at the same time the brasses to the strap and the strap to the rod end.
Fig. 2380.
When the rods are finished so far as the fitting of its various parts are concerned, the brasses should be marked so that the bore, when bored out, will leave an equal thickness of metal between the brass and the strap on each side of the bore, while the rod will be of proper length. To accomplish this, mark on the outside face of the top brass two lines level with the faces which fit against the inside jaws of the strap, as shown in [Fig. 2380], a, b being the lines referred to. We then key up the brasses in their places in the rod and fasten a centre piece in the brasses at each end of the rod. Upon these centre pieces we first mark a line parallel with and central between the lines a, b, and then a line across the joint of the brasses if the joint faces meet, and in the centre of the space between them if they do not meet.
Before applying the trammels to test the rod length, the latter should be stood or placed in the position in which it works when on the engine; for all rods deflect by their weight, the amount of such deflection depending upon the position in which the rod is suspended. The trammels also deflect, it is true, but their deflection is allowed for in setting them, whereas the deflection of the rod will not be accounted for unless it is trammelled when standing or lying in the position in which it works.
Fitting up Solid-ended Connecting Rods.—In fitting up solid-ended rods the side faces require to be filed up first and the jaws to receive the brasses next, taking care to file them out either square with the faces, or if slightly taper, as they should be, then each inside face should be an equal degree of taper to the side faces. This is necessary so that if the brasses are bored true to their own faces, the bore of the brasses at one end of the rod shall stand parallel to the bore of those at the other end.
The fitting of the keys and brasses is performed as described for strap-ended rods.