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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



147 



THE AMERICAN STEAM EXCAVATING MACHINE. 

 (" YANKEE GEOLOGIST.") 



( With an Engraving, Plate VI.) 



This machine, winch is the invention of the late Mr. Ottis, of New 

 York, is an application of steam power to the purposes of excavation 

 ant) dredging; and for the former purpose, appears greatly superior to 

 any thing which has hitherto been achieved in excavating machinery. 

 The accompanying engraving, which has been made expressly for our 

 Journal, by Mr. George Spencer, Mechanical Draughtsman, from the 

 original working drawings in his possession, presents the principal 

 side elevation (Fig. 1) of the machine, which brings all the working 

 parts sufficiently into view ; Fig. 2, a plan of the horse-shoe pulley 

 and crane top; the dotted lines show the position of the lower framing 

 or stage and boiler; Fig. 3, shows the crank shaft and gearing; 

 Fig. 4, the main drum ; Fig. 5, the main drum for working the exca- 

 vator ; and Fig. 6, a plan of the excavator. 



The whole of the details of this machine, which are very elaborate 

 and complete, of course cannot be attempted in an article of this 

 nature; we will, however, describe as much of the details and its 

 principal feature as are necessary to a proper understanding of the 

 several movements of the machine, and then describe each of those 

 movements separately. The machine consists of a strong horizontal 

 wooden framing or stage A, mounted upon two pairs of railway 

 wheels B, for locomotion, which run on temporary rails, laid down as 

 may be required ; on the one end of the stage is fixed a cylindrical 

 boiler C, and the gearing for turning the crane round. In the middle 

 is placed the gearing for working one of the motions of the exca- 

 vator D ; and, at the other end is placed the wooden crane E, in form 

 similar to an ordinary timber crane, on the diagonal brace of which is 

 placed a platform f, on which an assistant stands; and gearing U, for 

 working another motion of the excavator D. To support the machine 

 laterally, strong brackets or arms project on either side, the ends of 

 which are furnished with screws to adjust the machine to the ine- 

 qualities of the surface of the ground. 



The excavator or shovel D, (Figs. 1 and 6,) is formed of stout 

 boiler plate, and is firmly rivetted together; it is of a box shape, 

 having one end open ; on the lower edge are four tangs or points, 

 which serve to penetrate and loosen the soil ; the other end is hung 

 on swivel hinges, and fastened by a spring d, which may be set at 

 liberty by means of the lever and rods a, Fig. 1. 



The machine is made to perform three distinct movements; 1st, the 

 digging movement; 2nd, the turning movement, and 3rd, the locomo- 

 tive movvement. 



The Digging Movement consists of two motions, one for drawing 

 the excavator forward, and the other for driving it into the ground, 

 both of which is done simultaneously ; the first motion is performed 

 in the following manner. On the horizontal stage A, and in front of 

 the boiler C, is placed a small high-pressure engine, (not shown in the 

 engraving,) the connecting rod of which acts upon the crank c, and 

 gives a rotary motion to the shaft L, and with it the pinion /, (Fig. 3,) 

 which works into the large wheel M, mounted on the shaft N, upon 

 which is fixed a large channelled barrel or drum n, (Figs. 1 and 4,) 

 round which the hauling chain O, is coiled; this chain passes upwards 

 through the hollow crane post, over the indented pulley P, to a double 

 pulley fixed at the jib head, thence round the blocks R, to which the 

 excavator is suspended, as the chain wound up draws the excavator 

 out of the ground both in a forward and upward direction, when 

 driven into the ground by the second motion. This last motion is 

 communicated by the chain traversing over the indented pulley P, to 

 another gearing. On the axle of the indented pulley P, is fixed a 

 bevelled wheel v, (Fig. 2,) which works into a similar one »', (Fig. ],) 

 mounted on to the upper end of the oblique shaft V, on the lower end 

 of which is a corresponding bevelled wheel v", working into another 

 w, fixed upon the shaft W ; upon this shaft is a pinion w', which takes 

 into the large spur wheel it', mounted upon the shaft U, upon which 

 is a channelled drum it, round which is coiled the chain s, attached to 



No. 68.— Vol. VI— May, 1813. 



the diagonal wooden arms S; on the lower end of these arms is fixed 

 an iron yoke, to which is suspended on pivots the excavator. By this 

 arrangement, as the main chain O, passes over the pulley P, motion is 

 communicated to the shaft U, for the purpose of forcing downwards 

 in a diagonal direction the arms S, and with them the excavator into 

 the ground. A man stands upon the stage/, for throwing in and out 

 of gear this apparatus, and to regulate the motion for lowering or 

 raising the excavator. 



The next motion to be described, is for the purpose of turning the 

 crane round either to the right or to the left; this is effected by ano- 

 ther gearing in the following manner. On the first crank shaft L, is 

 fixed a bevelled wheel /', (Fig. 3,) which works into a similar wheel g, 

 mounted on to the end of a horizontal shaft G, upon which are placed 

 loose two bevelled wheels g' g", either of which can be thrown in or 

 our of gear so as to work, as may be required, into the large bevelled 

 wheel h, mounted upon the shaft H ; upon this shaft is a pinion h', 

 which works into the wheel j, fixed on the shaft J, upon this shaft is 

 fixed an indented pulley /, round which the chain r, is coiled, and 

 passes upwards over pulleys s, round either side of the horse shoe 

 pulley, to the ends of which it is fixed by iron bolts ; the horse shoe 

 pulley is fixed by means of strong iron stays to the crane, and when it 

 is made to revolve the crane jib is turned round on the stationary post 

 /, either to the right or to the left as may be required, and empties 

 the contents of the excavator into a wagon or barrow. 



The Progressing Motion is effected by placing on the hind wheel 

 axle a strong wheel, shown by a dotted circle b, (Fig. 1,) which com- 

 municates with a pinion b', on the shaft i, by an intermediate pinion 6", 

 as shown by a dotted circle ; motion being given to the shaft H, by 

 the bevel gearing, described in the last motion, a forward or backward 

 motion of the machine is obtained. 



We have no precise data as to the cost of the machine or the quan- 

 tity of work that can be performed by it, further than a short para- 

 graph we gave in the last November number of the Journal, wherein 

 it states that the machine is capable of digging 1000 cubic yards of 

 earth per day, and that a machine complete costs about 6000 dollars 

 in America. 



ROOF OF THE RIDING SCHOOL AT NEWCASTLE- 

 ON-TYNE. 



(With an Engraving ; see Plate VI.) 



Sir — Having expressed your intention of giving some examples of 

 construction useful to the student, in the description of the roof of the 

 Polytechnic Institution, Vienna, in a former number of your excellent 

 work, I am induced to send you the enclosed sketch, on account of the 

 similarity of construction in the two, and they being the only cases 

 I know extant where support is obtained from the side walls of the 

 building on a line lower than the level of the tie beam, I shall first 

 describe the peculiarities of the Vienna roof, and then of the roof at 

 Newcastle. The former is 56 ft. span, and formed of curvilinear ribs 

 12 in. sqaare, standing on a set-off of the wall considerably below the 

 wall plate, and the crown of the rib rising about as much again above 

 it, the slope or pitch of the roof being made uniform with rafters of 

 smaller scantling. The ribs are cut out to the sweep of the curve, and 

 are not laminar ribs, by which mode much additional stiffness is ac- 

 quired. It is evident the arch is the principle of construction. The 

 covering is copper, the weight being about 100 lb. per square, whilst 

 tiles are 6501b. weight per square. The annexed engraving exhibits 

 the roof constructed over the circus or riding school at Newcastle, 

 erected in 17S9, under the superintendence of Mr. David Stephenson, 

 architect, who was a resident and practised in Newcastle; he Was the 

 architect of the Theatre Royal and All Saints' Church, and architect 

 to His Grace the Duke of Northumberland, &c. The span of the roof 

 is 64 feet in clear of the walls, the length about 75 ft., and the height 

 of the room from the floor to the crown of the arch, or horizonal beam 

 at the foot of king post, 30 ft. The tie beams and principals are 12 ft. 

 by 6ft. placed 104ft. apart. The struts from king post 8ft. by Sft. 



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