DETAILS OP (PADDLE-WHEEL)
208
being the Messrs. Dudgeon, from whose work-ing drawings those engraved were compiledand produced. This arrangement is termedthe worm, wheel, and lever motion, whichthe following description will pourtray. Theside elevation shows the eccentric link,sliding quadrant, and working levers at halfstroke; the entablature and trunnion blockbeing shown complete, beyond the gear. Aportion only of the condenser is representedin section ; but a complete sectional elevationof the discharge chamber is depicted, to showthe means for supporting the starting wheelshaft, which is a tube cast with the chamber,and a loose collar on the outside prevents alateral movement. The hand wheel is keyedon the shaft, and the horizontal projectinghandle on the wheel is for the purpose of quickmanipulation, when required. The shaft hasformed with it, at the other extremity, acoarsely pitched screw, generally termed aworm. A toothed quadrant gearing with theworm motion, at right angles to that of thestarting wheel, is acquired. The quadrant iskeyed on a single shaft, the latter being sup-ported in brackets, secured to the side of thechambers. At the ends of the shaft, leversare keyed and connected to the links by rods,thus any motion given to the starting wheelis transmitted to the links.
The location of the working levers andquadrant, in relation to the starting wheel, isseen in the plan, one set only being repre-sented. The levers are supported by plum-mer blocks—seen in elevation only—securedto provisions formed on the cylinders. Thedotted curves seen in the elevation of thechamber are explained in the plan, being
the spaces requisite for the action of themotion levers. The principle of this ar-rangement is so obvious from the drawings,that it is almost needless to state that, onmotion being imparted to the wheel, theworm acts on the toothed quadrant, andthe levers, by their connection to the link,shift the same, and thus the desired effectis attained.
The following dimensions are the practice
of Messrs. Dudgeon, for a pair of engines
200
horse power nominal collectively:—
Ft.
In.
Motion for Slide Valves .
,
0
51
Diameter of Central Bearing of Working Lever
0
4
Diameter of End Pins
0
2
Direct Length of Levers from Bearing
1
8*
Radius of Slot in Sliding Quadrant
,
2
33
Width of Slot in ditto
0
8i
Thickness of Slot in ditto .
0
3
Radius of Link ....
5
6
Width of Slot in Link
.
0
8*
Thickness of Link ....
0
2*
Diameter of Block Pin
0
2f
Travel of Sliding Block
.
1
6
Length of ditto ....
.
0
5*
Diameter of Eccentric Rod’s Pins
,
0
2
Diameter of Band Bolts
0
li
Diameter of Starting Wheel Shaft
0
2
Radius of Toothed Quadrant
0
7#
Diameter of Weigh Shaft .
#
0
3*
Diameter of Worm ....
0
4
Diameter of Connecting Rods
,
0
If
Diameter of Starting Wheel to centre
of
handles .....
3
0
SINGLE ECCENTRIC MOTION AND STARTINGGEAR.
To correctly understand any branch ofscience or arrangement of mechanism is firstto become acquainted with the requirements.From this cause the engineer develops all hisproductions, and obviously also whether one,two, or more attainments are required at once,