US176541A - Improvement in raising and lowering screw-propellers - Google Patents

Description

2 Sheets-Sheet 1.

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NITED STATES PATENT Orman.

IMPROVEMENT IN RAISING AND LOWERING SCREW-PROPELLERS.

Specification forming part of Letters Patent No 176,54 l dated April 25, 1876; application led April 5, 1ere.

To all whom tt may concern Be it known we, MERWIN McKAIG and WALTER J. MUNc/isrrnn, of Cumberland, in the county of Allegheny and State of Maryland, have invented Improvements in Engines and Propellers for Propelling Canal-Boats by Steam; and that the following is a full and complete description thereof.

The prospect that steam will soon supersede animal power in the propulsion of boats on canals has led to many improvements in the structure of engines, Sto., with a view to their adaptation to the peculiar requirements of canal navigation. A principal requirement of the case is facility for raising and lowering the propulsion-wheel because, when loaded, the boat will barely clear the bottom, and said wheel must then be entirely above the line of the keel, and when unloaded she draws but a few inches of water, and the propulsion-wheel, if unchanged in position, would not then be suflicientlysubmerged. It has therefore been heretofore proposed to place the engine upon a horizontal frame, mounted upon transverse bearings, about midway between the said engine and said wheel, so that as the said wheel is lowered the engine is correspondingly raised, and vice versa. The purpose of this arrangelnent is to simplify the structure, to enable the engine to apply its force directly to the rotating shaft at all times, because their relative positions are always unchanged, and to dispense with universal joints, or substitutes therefor, in changing the direction of motion. This principle of structure has been employed with paddle and screw-propellers; andhence we do not claim anything more than the peculiarities of structure hereinafter fully described, whereby a vertical engine and screw-propeller are rendered more simple in structure, compact, and eiiicient, and the propeller and engine more readily handled than heretofore.

With this general statement of the foundation of our invention, we will proceed to enumerate specitically'the points'of our improvement:

It consists, rst, in a vertical engine-frame bearing the cylinder at its top, and provided with a long tubular sleeve, projecting from its lower end perpendicular to the axis of the cylluder, for the reception of the crank-shaft,

said frame being mounted upon trunnions, so that it may be tilted to elevate or depress the projecting end of the crank-shaft, upon which the propeller is mounted second, in so locating the trunnions of the engine-frame that their axis will cut the intersection of the axis of the crank-shaft and piston-rod, or nearly so; third, in a lifting apparatus, applied to the rear extremity of the crank-shaft tube, whereby the support of the propeller is effected without strain upon the crank-shaft; fourth, in the oscillating packing boxes, through which the shaft-sleeve passes outward; fifth, in the peculiar windlass for raising and lowering the propeller; sixth, in the apparatus for raising the propeller; seventh, in locating the crank so near the bottom of the boat that the shaft deflection may be above the horizontal plane when loaded, and, therefore, a less downward detlection when light, whereby the end thrust of the crank-shaft may always approximate more nearly to the direction of the axis of the boat than heretofore.

B is the vertical engine-frame, upon the top of which the steam-cylinder E is mounted. The frame B is provided with two laterallyprojecting trunnions, A, which rest -in the pillow-block boxes, so that the cylinder and frame may vibrate upon said bearings. Opposite the trunnions A the frame B is provided with an arm, M, which projects from said frame perpendicular-ly to the axis of the piston-rod a. Within the arm M there are two pillow-blocks, with boxes G G, and said arm M is prolonged by a tubular sleeve, (l, which is securely bolted or otherwise secured to the end of said arm. At the extremity of the tube C there is fitted a thimble bearing or box, D, in axial line with said tube and with the blocks G G. These bearings are to receive the crank-shaft F, the crank whereof is between the boxes G G, and in the plane of the piston-rod c. The tube C is suflciently long to project through the slot b in the stern-post of the boat N, and the propeller-screw O is mounted on the shaft F, close up t e end of said tube. At the rear end of e tribe C outward there is a sling or box, attached to the lower end of a strap or chain, W, which extends upward to a windlassf Y, above the load water-line of the boat N, for the purpose of suspending the rear end of said tube and crank-shaft, without strain upon said shaft.

From the above description it will be perceived the engine and shaft have a fixed relation to each other, and that the axis of roA tation of the shaft is always coincident, with the axis of the crank hence there is no loss of power due to a change of direction or interposition of gearing, and that the crankshaft has a Second movement upon the transverse axis of the trunnions A, whereby the propeller may be raised or lowered, and the exigirleframe and cylinder partake of this movement. The axis of the trunnious A cuts the axis of the piston-rod at its intersection with the axis of the crankshaft, and therefore the cylinder E vibrates upon said trunnion in a horizontal direction, and does not require extra head room below deck, as those engines do which nlove upon transverse axes, located between the engine and propeller. This of itself is a material advantage, when economy of space is an element to be considered, and permits us to use within the space heretofore occupied by the engine a much taller frame and longer connecting-rod than hitherto has been possible. This location of the trunnions also substantially balances the weight of the engine and frame, and offers a solid abutment in the line of the piston thrust, and thereby relieves the frame of much racking strain and vibration, which has heretofore occasioned trouble, and the frequent necessity for re pairs.

A stuffing-box, h, prevents the escape of water from the sleeve c into the engine-room.

Itis well understood that canal-boat pro pulsion by steam requires the ready raising or lowering ofthe propeller, because the ei'ective action of the screw requires it to be wholly or nearly submerged, and this cannot be when the boat is unloaded, if the screw remains above the line of the keel, in which position it must be when loaded, and it is also apparent that the greater the deflection of the propellershalt below the horizontal the less will be the propulsivc power ot the screw, because a part of said power, proportionate to the shaft dedection, is consumed in raising the stern of the boat. It is therefore of importance to obtain the required lift of screw with the smallest possible angular deflection ofthe shaft, and this result is one of the effects of the location of the trunnions at the forward end ofthe crank-shaft, and thereby the angular deliection of the crank-shaft is only onehalf the deflection of shaft as heretofore constructed.

By locating the trunuions A near the front end of the crank-shaft we are enabled to place said bearings close down to the floor, and thereby' depress the front end of thc crankshaft below thel center of the propeller when raised to load position, and said shaft will then have a slight upward angular deection, and in a corresponding degree the downward dellection is reduced when the boat is unloaded. We thereby obtain an average thrust more nearly horizontal than has heretofore been possible.

Heretofore with engines of this class it has been necessary to place an adiustable support beneath the frame, forward of the transverse axis of said frame, because the preponderance of weight is in front of said axis. This structure renders the engine-frame practically fixed in any adjusted position, audit' the propeller, when submerged, comes in contact with any fixed object, as it is liable to do when running near to the bank in passing another boat, the propeller may be broken or its shaft bent, because it is unyeldingly held in position. No accident of this sort can happen with our e11- gine, because the preponderance of weight is behind the trunnions, and therefore the rear end of the crank shaft and its inclosing-sleeve C may be left free to rise up at any moment if the blades of the screw 0 shall strike any unyielding thing with sufficient force.

lt is necessary to provide proper devices for preventing the entrance through the slot I, and to obviate the difficulty of packing a slide. We have constructed a compound box with circular lines of comparatively short radius, which are not only radiallyshaped, but easily packed. The first ot' these is the larger box J, having top and bottom edges forming arcs of a circle, Whose axis is coincident with thc axis of the trunuion g. This box J is inclosed by a packing-gland, K, so that it may turn upon its trunnions without admitting water. A second smaller box, I. with circular periphery, but shorter radius, is placed ill the inner edge of box J, and packed with a gland, i. The sleeve() passes through the box l with a stuiiing-box, lc. The box l has trunnion-pins g inserted through the ends of straps, which are bolted to the sides of said box. A movement ofthe crankshaft in a vertical plane only is necessary, and therefore the boxes l and J do not require to be of greater thickness laterally than is required by the diameter of the shaft. This is clearly shown in Fig. 5. The chain W passes over the windlass-pulley Y, and thence down to the piston-rod m in the steam-cylinder Z, which takes steam through the pipe a when the valve p is opened. When the propeller is to be raised the valve p is opened, and steam admitted to the top of the cylinder z, whereby the piston is forced to the bottom of said cylinder, and the chain W accordingly pulled over the windlass-pulley Y. When the piston reaches the bottom of the cylinder Z, or just before reaching the bottom thereof, a hole in the side of the cylinder is uncovered by the passage of the piston, and the steam exhausts, but the propeller is not thereby permitted to descend again, because the windlass-pulley is made in two parts-that is, a sheave over which the chain passes, and a wormwheel gearing with the worm-screw Yand these parts are connected by an internal ratchet on the wormwheel, and suitable pawls engaging therewith on the sheave, whereby the latter is permitted to turn freely in one direction independent of the worm-Wheel, but incapable of moving in the other direction, except as the worm-wheel moves with it. Therefore the propeller is raised quickly by steam-pressure, but is lowered again only by the act of'the attendant, who turns the Worm-screw shaft at will for that purpose.

When one boat is passing another the propeller-blade may sometimes take the ground, and as the engineframe is free to move on the trunnions A the propeller can rise up when it encounters such an obstruction, and there is, therefore, no risk of springing the shaft, as would certainly occur if the engine was fixed in position, as has heretofore been the case; but the inertia of the engine-frame is considerable, and while the sleeve C and shaft will not spring so as to become set before moving the said frame, still any deviation will cause the shaft to cramp more or less in the boxes and cause them to wear, and we therefore have joined the shaft to the crank by a coupling, s, which is slightly exible, andwill prevent any cramping of the shaft F in its bearings, even though the sleeve C should deviate considerably from its true line.

Having described our invention, what We claim as new is 1. rlhe vertical engine-frame B, mounted upon trunnions A, and provided with the tubular arm C, extending through the stern of the boat and provided with the boxes G G and D, combined with the crank-shaft F, mounted in said boxes.

2. The vertical engine-frame B, provided with an arm, C, havin g a box at its extremity for the reception of the crank-shaft combined with trunnions A A, Whose axis is in line with, or nearly so, the intersection of the axes of the crank-shaft and piston-rod.

3. The vertical engine-frame B, mounted upon trunnions A A, and provided with the tubular arm C, extending through the stern of the boat for the reception of the crankshaft F, combined with the lifting-chain W, whereby the engine-frame may be tilted Without strain upon the crank-shaft.

4. The vertical engine-frame B, provided with the arm C, and mounted upon trunnions A A, combined with the crank-shaft F, and the double-jointed packing-boxes I J K, substantially as set forth.

5. A crank-shaft, F, mounted in bearings oscillating on a transverse axis at its front end, combined with a suspension-box, X, at its rear end outside of the boat, and the windlass Y and worin-screw Y', substantially as set forth.

6 A windlass, Y, composed of a chainsheave, with a Worm-Wheel provided with an internal ratchet, d, and coupled with a pawl, e, combined with a worm-screw, Y', substantially as set forth.

7. The vertical engine-frame B, mounted upon trunnions and provided With the tubular extension-arm C, for the reception of the crankshaft F, combined with the suspensionchain W, windlass Y, and steam piston and cylinder Z, as set forth.

8. The vertical engine-frame B, mounted upon trunnions A A, and provided with a tubular sleeve or arm, G, for the reception of the crank-shaft F, and arranged so that the said crank-shaft may be adjusted with an up- Ward or downward inclination from the crankend, as may be desired.

9. The double-jointed packing-boxes I J K, combined with the sleeve G and shaft F, which is thereby permitted to rise or fall freely, and

Without cramping in the packing.

10. The packing-boxes I J, constructed with their vertical longitudinal section circular, as shown in Fig. 2, combined with axial trunnions or pivots .g y, as set forth.

11. A vertical engine-frame, B, mounted upon trunnions A A, and provided with a hollow arm or sleeve, C, with bearings Gr Gr D for the reception of a crank-shaft, combined with a crank-shaft in two parts, coupled together with a slightly-dexihle coupling, substantially as set forth.

i MERVVIN MCKAIG.

WALTER J. MUNGASTER.

Witnesses:

WM. L. MORGAN, Unas. WEIsKE'rrLE.

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