Engineering reminiscences contributed to "Power" and "American machinist"

by Charles T. Porter

The above [left-hand cut] shows the automatic lubricator of the eccentric and the cross-head pin. The stud A, on the eccentric strap and on the strap of the connecting-rod, carries a curved blade, a, which at the beginning of each forward stroke rises to take the drop of oil from the stem of the sight-feed lubricator. This is set on an arm fixed on the cap of the main-bearing and on a bridge between the upper guide-bars. The drop is made sure to come to this central point by a wire B filling the brass tube, grooved on opposite sides and terminating in a point.

The automatic lubrication of the crank-pin presented a still more serious problem. It was solved by the construction shown, in the [right hand view], which will be understood without further description. It will be seen that here the oil tube is inclined, and the drop follows it to a point on its lower side. Both these lubricators proved absolutely reliable. The last one is equally applicable on double-crank engines.

Dimensions of Cylinders.			Revolutions of Crank per Minute.		Travel of Piston in Feet per Minute.	Indicated Powers.		Fly-wheels. Made when Practicable to Serve also as Belt-Drums.			Driving Belts.
Bore.		Stroke.				Without Conden- sation.	With Conden- sation.	Diameter.		Weight of Rim.	Velocity.	Width.
Inches.		Inches.				Horse Powers.	Horse Powers.	Feet.	Inches.	Lbs.	Feet per minute.	Inches.
6		12	350		700	25		3		350	3300	9	single.
7		12	350		700	35		3	6	400	3850	10	„
8		16	280		746	45	60	4		650	3520	12	double.
9		16	280		746	60	75	4	6	700	3960	12	„
10		20	230		766	75	100	5		1300	3610	14	„
11	.5	20	230		766	100	125	5	6	1450	3970	14	„
13		24	200		800	130	160	6	6	2100	4084	18	„
14	.5	24	200		800	160	200	7		2350	4400	20	„
16		30	165		825	200	260	8		4000	4150	26	„
18		30	165		825	250	330	9		4000	4670	30	„
20		36	140		840	320	400	10		6000	4400	38	„
22		36	140		840	400	500	11		6000	4840	42	„
24		42	125		875	480	620	12
26		42	125		875	560	730	13
28		48	112	.5	900	670	870	16
32		48	112	.5	900	870	1140
36		48	112	.5	900	1100	1430
40		48	112	.5	900	1360	1750
44		48	112	.5	900	1600	2100

The powers are those given by an initial pressure of 85 lbs. on the square inch, cut off at about one quarter of the stroke. For the best economy steam should not be cut off earlier than this, unless a higher pressure is carried. At the latest point of cut off, the powers developed are double those given in the above Table. The engines can be worked under locomotive pressures, with corresponding increase of power.

After considerable study I finally adopted the above table of standard sizes and speeds, covering the ground from 25 horse-power up with nineteen sizes.

As the bed could not be reversed, I needed both a right-hand and a left-hand bed for each size. I avoided half of this expense in patterns by planning two diameters of cylinders with the same stroke, and making one bed answer for both.

Until I found something else to do, I employed myself in preparing complete drawings for three or four smaller sizes of engines; a work which afterwards proved exceedingly useful.

CHAPTER XXI

Production of an Original Surface Plate.