444 
STEPHENSON’S PATENT 
to the ends of each of these levers by a steel pin passed through them, with a 
small pin and washer at the end, to prevent its getting loose; the other ends 
of the links m m", being attached in a similar manner to a socket on the valve 
spindle which is guided at its end by an eye in a small pillar fixed on to the boiler. 
The eccentric rods (f e"', taking hold of the bottom levers h" hmake them move 
backwards and forwards with the eccentrics; and the top levers l" V", connected with 
them by the weigh-bars i" i'", communicate the motion to the valve spindles 
by means of the links, m' w!"; the levers h" and 1" being of the same 
length, the motion of the slide valves is the same as the throw of the eccentrics, 
or three inches, as before stated. The links allow for the oblique actiom 
of the top levers which move in an arc of a circle, instead of a straight 
line as the valve spindle. The pins and eyes of the levers are all of steel, to 
diminish the wear, and are fitted very accurately, so as not to allow any shake 
when the motion is rapidly reversed at the end of each stroke, and that the slide 
may be moved the full three inches. The eccentrics E' and E" are placed at right 
angles to each other, that they may be both in the same relative position to the 
respective cranks; and they are fixed in such a position with regard to the crank, 
that the port is full open, or the slide at the end of its motion, when the piston is 
at half stroke, as shewn in Plate XC. The eccentrics are therefore at right angles 
to their respective cranks, and they have to be fixed a quarter of a revolution 
behind the cranks, in order to move the slides as much in advance of the pistons; 
because the levers h" and l" reverse the motion, so that when the slide has to be 
pulled back, the eccentric rod must be pushed forward. 
Reversing Gear.—The eccentrics, E' E", are placed so as to work the engine for 
ward ; and when the crank is down, as in Plate XC., to cause the piston to be pushed 
back, and pulled forward when above the axle, and thus cause the wheels to turn 
round in the direction of the arrow, and propel the engine forward. In order to 
make the engine run in the opposite direction, two other eccentrics, F 7 and F", are 
necessary, which are placed exactly in opposite directions to the former ones, or 
at the extreme back position when the former ones are at their greatest throw 
forward; their rods, f"f"\ have forks at the ends, similar to the other eccentric 
rods, and levers, n" ri", corresponding to them are fixed on the other ends of the weigh- 
bars i i"', exactly like the levers h" h'". The four eccentric rods have pins fixed 
into them below the forks, and attached to the suspending rods, o o", o"o"; the 
two middle rods, o o", for the working eccentrics, E' E', being connected at the 
top to a cross head at the end of the horizontal lever p", and the other two, 6" o'", 
for the reversing eccentrics, forked at the top, and attached to the levers p" p",