US3779319A

US3779319A - Mobile snow working apparatus with adjustable height flailer

Info

Publication number: US3779319A
Application number: US00247142A
Authority: US
Inventors: T Pease
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-04-24
Filing date: 1972-04-24
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

A trailer for breaking and pulverizing crusty and/or icy snow cover on a ski slope comprising a frame provided with wheels by means of which it may be transported over open roads and/or bare ground to a ski slope and skis for traversing the slope. The trailer frame has on it a motor-driven drum to which are attached a plurality of chain flails having at their distal ends breaker elements for cutting through the hard cover, and there are adjustable mounting members connecting the skis to the frame so as to enable raising and lowering the frame and hence the drum relative to the skis so that on the one hand the drum may be supported above and spaced from the snow cover to permit the flails to be turned at a rapid rate about the axis of the cylinder and to cause the breaker elements at their ends to break through the crust and on the other hand may be lowered into substantial engagement with the cover to cause the flails to become traction elements between the drum and the cover.

Description

llnited States Patent Pease Dec. 18, 1973 MOBILE SNOW WORKING APPARATUS FOREIGN PATENTS OR APPLICATIONS WITH ADJUSTABLE HEIGHT FLAILER 108,884 ll/l939 Australia 280/l2 [76] Inventor: Theodore J. Pease, 461 Faunce 47,225 4/1911 Austria .1 172/45 C Rd., N th D t th, alia or ar OTHER PUBLICATIONS [22] Filed Apr 24 1972 R.P.U. Note U.S.A. case 984914 copy is provided.

[21] PP 247,142 Primary ExaminerRobert E. Pulfrey Related Application Data Assistant ExaminerEugene H. Eickholt [63] Continuation-impart of Ser. No. 9,267, Feb. 6, 1970, Atmmey*Rbert Gammons abandoned.

[57] ABSTRACT [52] i ga' agz i2 3;: A trailer for breaking and pulverizing crusty and/0r d 1 3 E icy snow cover on a ski slope comprising a frame pro- [51 Hm Cl A0") 4 vided with wheels by means of which it may be trans- [58] Field l6 2 92, ported over open roads and/or bare ground toa ski 172/45 240 5 7 slope and skis for traversing the slope. The trailer R 2 08 i 56/29"280/8 9 frame has on it a motor-driven drum to which are at- E tached a plurality of chain flails having at their distal ends breaker elements for cutting through the hard [56] References Cited cover, and there are adjustable mounting members connecting the skis to the frame so as to enable raising UNITED STATES PATENTS and lowering the frame and hence the drum relative to 2,967,061 l/l96l Schwab 280/9 X the kis so that on the one hand the drum may be up- $503,620 3/1970 Knskfimch 280/1 ported above and spaced from the snow cover to per- Z 32; lsobbms mit the flails to be turned at a rapid rate about the axis 3x i i l ""i' X of the cylinder and to cause the breaker elements at l'55275O 9/1925 56/29 X their ends to break through the crust and on the other 3 4/194] 241/195 hand may be lowered into substantial engagement 3363.836 8/1966 Kucera n 56/29 X with the cover to cause the flails to become traction 2,965,320 12/1960 Pierson 241/185 R elements between the drum and the cover 2597,053 5/l952 Bartch et al. t 56/29 X 2583.767 1/1952 Daignas 56/29 x 14 Clams, 11 Drawlllg Figures 984 9i4 l2/l9l() Heidenheimer 280/9 J7 J7 z 2 j; ---r\ i, 17 6' J r r. l t 5 J? r- 4 L I W A 7 lk r r PATENTEIJBEE 18 can 3.779.131 9 v SHEH 2 BF 4 PMENTEHnzcmusza 3379.319

sum BM 4 FIG.6

PATENTED 05c 18 ms SHEEI l 0F 4 FIG? FIGB

MOBILE SNOW WORKING APFARATUS WITH ADJUSTABLE HEIGHT FLAILER This application is a continuation-in-part of copending application Ser. No. 9,267, now abandoned filed Feb. 6,1970.

BACKGROUND OF THE INVENTION US. Pat. No. 3,463,548 shows an apparatus for breaking up and conditioning hard snow on ski slopes wherein there is a trailer provided with skis by means of which it may be moved along a ski trail and a motordriven drum supported thereby on which there are fixed a plurality of rigid cleats. As constructed, the drum is supported so that its lower side in its operative position is below the surface of the cover and forward progress is dependent upon the cleats eating away the crust so as to permit the cylinder to be moved forwardly. The action is a progressive eating away of the hard cover as the apparatus advances. Ice breakers and snow crushers are also shown in the U.S. Pats. to Lommen 2,606,011 and Konucik 3,340,626 respectivelythe one showing chain-type flails attached to drums for rotation therewith to break up ice on highway and the other showing crusher cups secured to cutting blades to break up and throw the broken snow. Neither of these pieces of apparatus is suitable for operating on ski slopes. It is the purpose of this invention to provide an apparatus which, like the Kelly US. Pat. No. (3,463,548) apparatus is adapted to be drawn along a ski trail but in contrast thereto is provided with flails such as shown in Lommen US. Pat. No. 2,606,011, to provide for impact breaking and pulverizing not available with the Kelly apparatus and in such combination as to facilitate negotiating steep and slippery slopes both when travelling upwardly and when travelling downwardly without side slip and/or jack-knifing and to further provide an apparatus which is adapted to be easily towed over highways and bare gound to the slope and thereafter to be towed over the snow cover of the ski trails for breaking up and conditioning of the snow thereon. Other objects are to provide for easier manipulation of the apparatus with less danger to the operator; for better beater action and hence pulverization and conditioning of the cover; and finally for more economical use of power.

SUMMARY As herein illustrated, the trailer comprises a frame, spaced parallel skis on which the frame is supported, means on the trailer frame for connecting it to a tractor for movement of the ski-equipped trailer on the snow cover, a drum mounted on the frame rotatable about an axis transverse to the skis, flails on the drum comprising elongate flexible elements attached at one end to the surface of the drum for rotation therewith, adjustable means mounting the skis to the frame such as to enable moving the skis and frame relative to each other to raise and lower the drum relative to the cover on which the skis rest, said drum normally being held by adjustment of the skis and frame relative to each other at a level above and spaced from the cover such that only the distal ends of the flails while travelling about the axis of the drum engage the cover as they travel between the lower side of the drum and the surface of the cover, and means for, at times, effecting movement of the skis and frame to lower the drum to a position adjacent the cover such as to engage the portions of the flails extending from the drum to their distal ends between the lower surface of the drum and the snow cover as they travel therebetween to cause the flails to become traction elements. There is also means for providing an air cushion between the tread surfaces of the skisand the snow cover on which they rest.

The invention will now be described in greater detail with reference to the accompanying drawings, wherein:

FIG. l is a side elevation of one form of the trailer shown partly in section;

FIG. 2 is a plan view of the trailer shown in FIG. 1;

FIG. 3 is an enlarged end view of a beater drum;

FIG. 4 is a fragmentary section taken on the line 44 of FIG. 3;

FIG. 5 is a plan view of the drum unfolded;

FIG. 6 is an end elevation of an alternative form of trailer;

FIG. 7 is a side elevation taken from the left side of FIG. 6;

FIG. 8 is an elevation of a single wheel mount;

FIG. 9 is a diametrical section of a single beater element;

FIG. Ill) is a top plan view of FIG. 10; and

FIG. 11 is an end view of FIG. 11.

Referring to FIGS. 1 and 2, there is shown a trailer having a frame 10 adapted to be alternatively supported on skis 20-20 or wheels 30--30. Each ski has fin keels 20a20a and is retractably mounted on scissor arms 5 and 7 pivoted at their upper ends to the frame 10. The lower end of arm 5 is pivoted to a fixed block 8 on the ski. The other arm 7 is pivoted to a block 9 slidable in a guideway iii. A screw 12 connected to the midparts of the arms, provided with a hand crank 12a, is adapted by rotation to spread the arms or to draw them together thus to lower or raise the skis with respect to the frame; for example, above the level of the wheels 30-30 to enable moving the trailer short distances on the highway or on bare ground or to move them below the wheels so as to support the structure on the skis for traversing snow-covered ground and in particular the ski slopes to be conditioned. A draw bar 13 (FIG. 2) is provided for connecting the trailer to a vehicle when moving it on its wheels and a second draw bar 114 is provided for connecting it to a tractor when moving it on its skis. For pulverizing and breaking up crusty and/or icy snow there is mounted on the trailer a drum 16 of about 12 inches in diameter and nine feet in length, for example, journaled at each end at right angles to the skis and to the draw bar in suitable bearing members l0a--10a on the frame. Secured to the circumference of the drum of approximately flails comprising chains 17 of chain fall quality extending from openings 18, FIG. 3, in the drum and having at their distal ends beater elements 19. The chains are of a length to allow the beater elements to penetrate the snow cover of which the skis ride to a depth of approximately 4 inches, more or less, depending upon the adjusted positoons of the skis relative to the frame. The beater elements may comprise studded solid iron balls; however, as will be later described, a special kind of beater element is preferred.

The drum 16 is driven by a gasoline engine shown schemically at 21 and includes an automatic transmission 22 provided with a shift control lever 23 which provides for three forward drive speeds, 1, 2 and 3, and one reverse drive R. The shift control lever 23 as well as a throttle (not shown) are connected by Boudin cables 25 to like remote controls on the tractor. The drum 16 and transmission 22 are connected by a belt 24 and pulley 26 in a 1:1 ratio. The drum and motor are usually turned at about 1,000 RPM constant speed as controlled by a governor 27 on the transmission output shaft. The drum may be driven at one of three forward speeds by shifting the control lever 23 in conventional fashion. From the exhaust to the engine a pipe 28 conducts the hot exhaust gases to within a hood 29 partly around the drum 16 to minimize icing of the drum, flails and related parts.

Depending from the hood and extending the length of the drum are breaker bars 3l31 (FIG. 1) against which the flails l7 fling snow and ice broken from the ground cover. The hook and breaker bars tend to confine the pulverized cover in an annular zone around the drum so that it is broken up not only by being beaten on the snow cover but also is broken up further by beating and tumbling within the hood. On an open slope the crusty snow is thus pulverized for a period and then redeposited in loose, uniform condition, providing an improved ski surface as the trailer is drawn up and down the slope.

As shown in FIGS. 3 to 5, the drum 16 has openings 18 which receive the end links of the chain flails 17 with a loop of the end links extending within the drum. The openings are elongately rectangular, conforming to the cross-wise dimension of the first link but too narrow to receive the second link at right angles to the first, the second link therefore tending to butt against the outside of the drum 16. As appears in FIG. 5, the openings are arranged in straight rows parallel to the drum axis. Corresponding sets of chains are anchored on the drum by rods 41 which extend lengthwise of the drum through loops of the end links of each aligned set. At one end of the rods are crooks 42 engaged in notches 43 at the end of the drum. An inner end plate 44 has clearance slots 46 for the crook and is held by cap screws 47 on blocks 48 welded to the drum. An outer end plate 49 attached by screws 51 to the inner plate covers the crook 42, preventing longitudinal movement of the anchor rods. By removing the three screws 51 in the cover 49 the rods 41 are readily accessible for removal and replacement of one or more of the chain flails 17.

While the chain anchoring openings 18 are aligned in equally spaced rows preferably parallel to the drum axis, chains in adjacent rows lie in different planes normal to the drum axis. For example, in FIG. the openings are shown as short vertical lines 4,6 102 and 104 on the unfolded drum 16. In this figure the

reference numerals

4, 6, 102 and 104 also represent the number of inches the opening so numbered is spaced from the lefthand end of the drum. Thus openings 6 lie in a plane spaced 2 inches from openings 4. With the exception of the

openings

4 and 104 at each end of the drum, openings in adjacent rows lie in different planes, as with openings 6 and 102. In a given row the openings are variably spaced from 2 inches apart to inches apart as with

openings

52 and 62. The result is that as the drum rotates, the chains flails, which tend to strike at the same spacing as the openings, do not repeatedly strike the same point or line of snow cover, but rather strike first one side and then the other of a portion of snow cover imparting lateral movement, fragmentation and pulverization of the whole surface area of the cover in the path of the drum flails. Moreover, the staggered spacing of the openings also forms counter-tuming spirals around the drum. For example, the mid-opening 4 and the lower opening 6 are in one spiral turning to the right, whereas the upper opening 104 and lower opening 102 are in a left-turning spiral. Most of the remaining openings are in right or left turning spirals which counteract the tendency of either set of spirals to pulverize the snow cover in a single direction lengthwise of the drum and leave the pulverized snow unevenly distributed in the wake of the drum.

As explained earlier, tractors and like vehicles designed for operation on unbroken snow surfaces are not safely operated at an angle along a contour line, and have traction and steering control limitations when operated uphill or downhill on full lines. When the substantial weight of the snow trailer is added to the tractors mass, there is a tendency toward loss of traction going uphill and downhill and the possibility of jackknifing the trailer-tractor rig going downhill. According to the present invention these problems are minimized by coordinating the snow-pulverizing action of the trailer with the pulling of the tractor.

When the tractor is drawing the trailer uphill the shift control lever 23 is set at one of the three forward speeds depending on the speed of progress of the tractor uphill or the degree of which the snow requires to be pulverized. The gasoline engine 21 is connected by a belt 24 to the drum 16 so that forward speed of the engine will rotate the drum in the same direction. As the trailer travels up the slop the forward rotation of the drum carries the flails around at a rather high speed so that the beater elements at the distal ends of the chains strike the crusty and/or icy snow cover at a very high speed. The impact is very high and so will break up the most stubborn patches of icy crust without retarding the forward progress of the apparatus and so with a minimum consumption of power since the drum itself does not engage the surface. If, at times, the slope becomes so steep or so slippery as to be difficult to negotiate without side slip, the skis may be raised with respect to the frame thus to lower the drum into substantial engagement with the ski cover and thereby to engage the flails throughout their entire length from their attached ends to their distal ends between the surface of the cylinder and the cover and in this manner to provide traction for a sufficient length of time to traverse the difficult area. When this area has been negotiated, the skis may be returned to their initial position by rotation of the screws 12 to raise the drum from the surface. This same traction may be taken advantage of when moving down a ski slope to prevent the trailer from side slipping or jack-knifing with respect to the tractor by adjusting the skis relative to the frame to bring the drum into substantial engagement with the snow cover and reversing the rotation of the motor by moving the shift control lever 23 to the reverse position R.

Narrow downhill trails are usually cleared or worn slightly concave. The snow tends to be swept by skiers from the center and piled at the sides. Such side piled snow can be broken up and returned to the center of the trail by conveyors mounted above the drum. The conveyors comprise two conduits 36-36 enclosing flight screws 3232 or like feed means disposed parallel to the drum on both sides of a vertical plane through the drum transversely of the trailer. The screws are connected to the drum by belts 33-33 and cary small pulleys 34-34 which step down their speed. The screws feed snow between an inlet 37-37 to each conduit and an outlet 38 on the lefthand side of the trailer. The inlets are located on oppositely directed tangents from the paths of the flails 17 within the hood enclosure 29 so that when snow is moved through the hood in either direction of rotation of the drum there is an efficient tangential path from the hood into one or the other of the conduits.

FIGS. 6 to 1 1 show an alternative form of the apparatus comprising a frame 40 (FIG. 7) on which there is mounted a drum 44, the ends of which are supported by a through shaft 46, the latter being rotatably mounted in suitable bearings 48-48 supported by blades 68-68 welded or otherwise fastened to the frame. Spaced from and parallel to the drum there are breaker bars 50-50, one at each side mounted longitudinally of the frame.

The frame is adapted to be supported by wheels 52-52 (FIG. 6) when the trailer is being transported along a highway or over bare ground to its place of use and by skis 54-54 at the place of use for movement over the snow cover which is to be broken up. According to this alternative structure the wheels are removed when the trailer is being used on the slope and to permit easily mounting and removing the wheels the frame has secured to it tubular wheel mounting members 56-56 welded or bolted to the frame at right angles to the axis of the drum. Wheel supports comprising shafts 58-58 (FIG. 8) are telescopically mounted in the tubular mounting members 56-56 and these have at their outer ends radial arms 60-60 (FIG. 8) which ex tend downwardly from the frame and have at their lower ends wheel bearings 62-62 on which the wheels 52-52 are rotatably mounted. The shafts 58-58 are non-rotatably mounted in the tubular mounting members 56-56 so that the arms 60-60 extend perpendicularly downwardly from the frame; for example, by making the tubular members and shafts of square crosssection.

The skis 54-54 are mounted to the frame with their longitudinal axes at right angles to the axis of the drum for movement relative thereto, each ski being connected to the frame by scissor arms 62 and 64 (FIG. 7). The upper ends of the

arms

62 and 64 of each set of arms are pivotally connected by means of a pin 66 to the bearing block 68. The lower ends are pivotally connected to the skis by

pivot pins

70 and 72. The pivot pin 70 pivotally connects the arm 62 to a block 78 fixed to the upper side of the ski. The pivot pin 72 connects the lower end of the arm 64 to a slide 74 slidably mounted on a track 76 fixed to the upper side of the ski. The arms are adapted to be drawn together or spread apart by means of a screw 80 which is threaded through a block 82 fastened to the arm 62 and a block 84 fastened to the arm 64. Reversible electric motors M are mounted to the underside of the frame and one of them is connected to each of the screws and there are controls connected to each motor adapted to be mounted in the cab of the tractor which is used to draw the trailer along the slope so that the operator may effect lowering and raising of the skis relative to the frame at will without having to dismount from the tractor and make this adjustment by hand as disclosed in FIGS. 1 and 2.

Ordinarily the apparatus is operated with the skis lowered relative to the frame in a position such that the ends of the flails will bite into the snow by a few inches at most. If greater or lesser penetration is desired the operator by extending or retracting the skis relative to the frame can change the degree of penetration.

The motor-driven arrangement for extending or retracting the skis also has the very great advantage that it enables the operator to quickly correct control movement of the trailer should it begin to side slip hen travelling upwardly or transversely along the slope or from overrunning or jack-knifing with respect to the tractor when travelling downwardly on a slope by retracting the skis to an extent to bring the surface of the drum substantially into contact with the snow cover or at least close enough so that the chains and flails are engaged between the surface of the drum and snow cover and so act on the one hand as traction means when the drum is rotating forwardly in the direction the apparatus is moving up the slope to aid in the upward movement or when the traileris moving down a slope to be reversed in a direction opposite the direction of movement to apply braking action to such downward movement.

As previously related, the flails are link chains 17 connected at one end to the drum and provided at their other ends with breaker elements which may be studded steel balls. preferably, however, the braker elements as illustrated in FIGS. 9 to 11, inclusive, comprise short sections of pipe connected to the ends of the chains 17. Pipe sections about 2 inches long and l-% inches in diameter are suitable and these are provided with axial slots 102 for receiving a loop 104 which in turn is connected to the last link in the chain 17. The link 104 is connected so that its plane is at right angles to the plane of the last link and so arranged that as the chain travels in a circle around the axis of the drum the axis of the pipe section will travel in a plane perpendicular to the axis of rotation so that the open ends of the pipe sections moving in the direction of ro tation strike the snow cover. A hard weld metal 108 is welded or brazed to the annular end surfaces ll 10 of the pipe sections. Preferably the pipe sections are comprised of a metal having a Shore hardness of approximately 80. When the drum is rotating at a rate of approximately 1,000 RPM the pipe sections at the ends of the chains are travelling at the rate of about 6,000 feet per minute so that when they strike the snow cover it can be readily understood that the impact is sufficient to break up the most stubborn patches of ice and reduce it to a consistency suitable for skiing purposes.

To prevent chunks of ice or stones from being driven laterally from beneath the frame by the flails and possibly injuring persons in the vicinity or the operator, a flexible curtain 112 is fastened to the frame all the way around so as to extend from the frame down to approximately the level of the skis in their most usual place of operation. This curtain may be comprised of rubber sheeting and is merely suspended from the frame at its upper edge. A hood 114 covers the drum.

The gasoline motor by means of which the drum is driven together with the drum itself and flails comprises a considerable weight and so imposes a considerable load on the tractor, particularly when moving uphill. In order to relieve this load and thus to enable easily starting uphill and maintaining uphill progress without overloading the tractor engine, the skis 54 (FIG. 7) are provided with a plurality of very small vertical air holes 112 which are in communication at their lower ends with the tread surface of the skis and at their upper ends with a manifold 114 which extends lengthwise of the top sides of the portions of the skis containing these holes within which is maintained an air pressure of approximately 14 psi. Pressure is continuously supplied to the manifold of each ski through a flexible conductor 116 which in turn is connected to a compressor 118 mounted on the frame and driven by the motor. The tread surfaces of the two skis is approximately 960 square inches and so by maintaining a pressure in the order of about 4 psi which can be easily done with a compressor or with an ordinary blower, air may be forced through these holes to substantially reduce the friction between the tread surfaces and the cover on which they rest.

To assist in connecting and disconnecting the trailer to the tractor by means of which it is moved either on its wheels or on the skis, a pair ofjack cylinders 8686 are welded or otherwise fastened to the frame, as shown in FIG. 6, which contain long lead screws 88-88, to the lower ends of which are rotatably fixed flat plates 9090. The upper ends of the screws are provided with cranks 9292 so that the plates may be lowered into engagement with the ground to lift the frame for engagement of its draw bar 94 with the tractor. A draw bar 96 is provided for connecting the trailer to a truck for road travel.

The flexible link chain structure of the flails with the pipe sections at their extremities not only provide ideal implements for breaking up crushed snow and ice but also serve to reduce protruding stumps, outcroppings of ledge, low mounds of earth, grass, brush, small shrubs and the like and thus provide for conditioning and/or grooming trails during the summer season preparatory to the winter season.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents falling within the scope of the appended claims.

I claim:

1. A trailer for pulverizing crusty and/or icy snow cover comprising a frame, spaced parallel skis on which the frame is supported, means on the trailer frame for connecting it to a tractor for movement of the skisupported trailer on the snow cover, a drum mounted on the frame rotatable about an axis transverse to the skis, flails on the drum comprising elongate flexible elements attached at one end to the surface of the drum for rotation therewith, adjustable means mounting the skis to the frame such as to enable moving the skis and frame relative to each other to raise and lower the drum relative to the cover on which the skis rest, said drum normally being held by adjustment of the skis and frame relative to each other at a level above and spaced from the cover such that only the distal ends of the flails, while travelling in a circle about the axis of the drum, engage the cover as they travel between the lower side of the drum and the surface of the cover, said adjustable means comprising pairs of arms, one pair for each ski, means pivotally connecting one end of each pair of arms to the frame, means fixed to the skis pivotally connecting the other end of one of the arms of each pair to the skis, means slidable along the skis in relation to the means fixed thereto pivotally connecting the other ends of the other arms of each pair of arms to the skis, screws connecting the midportions of the arms of each pair of arms, said screws being rotatable to spread or contract the arms relative to each other to raise and lower the frame with respect to the skis, and means for at times effecting rotation of the screws to lower the drum to a position adjacent the cover such as to engage the portions of the flails extending from the drum to their distal ends between the lower surface of the drum and the cover as they travel therebetween.

2. Apparatus according to claim 1, wherein the lastnamed means are motors connected to the screws.

3. Apparatus according to claim 2, wherein there are means operably connected to said motor means for effecting control thereof from a remote source.

4. Apparatus according to claim 1, comprising a motor operably connected to the drum so as to rotate the drum in a forward direction with respect to the movement of the trailer up a slope.

5. Apparatus according to claim 1, comprising a motor operably connected to the drum so as to effect rotation thereof in a rearward direction with respect to the downward movement of the trailer along the slope.

6. Apparatus according to claim 1, comprising beater elements fixed to the distal ends of said flexible elements, each beater element comprising a hollow cylinder of predetermined length and diameter supported at said end of the flexible element so that the axis of the cylinder travels in a plane perpendicular to the axis of rotation.

7. Apparatus according to claim 6, wherein each cylinder has open ends bounded by annular surfaces, the radial thickness of which corresponds to the wall thickness of the cylinder, and wherein a hard metal is applied to the annular surface at each end of the cylinder.

8. Apparatus according to claim 1, wherein the flexible elements are link chains, and the last link of each chain is connected to the wall of the cylinder within axially disposed slots therein.

9. Apparatus according to claim 1, wherein there are axially aligned tubular mounting members fixed to the frame parallel to and intermediate the skis and there are wheel supports telescopically engaged with said tubular mounting members and wheels rotatably mounted thereon, said wheel supporting members being removable from said tubular mounting members to permit removal of the wheels.

10. Apparatus according to claim 9, wherein the wheel supports comprise shafts adapted to be telescopically supported in said tubular mounting members, radial arms secured at one end to said shafts, and wheel bearings secured to the distal ends of the arms for mounting the wheels, and wherein said tubular members non-rotatably receive said shafts so that the arms extend perpendicularly downwardly from the frame.

11. Apparatus according to claim 9, comprising jack screws secured to the frame forwardly of the wheel supports for raising the frame to a position to enable coupling its draw bar to a towing vehicle.

12. Apparatus according to claim 1, comprising means for ejecting air at a predetermined pressure from the lower surfaces of the skis to produce air cushions between the tread surfaces of the skis and the cover on which they rest.

13. Apparatus according to claim 12, wherein said means for ejecting air under pressure from the tread surfaces of the skis comprise holes through said skis,

the lower ends of which are in communication with the tread surfaces thereof, manifolds fixed to the upper sides of the skis with which the upper ends of the holes are in communication, an air pump on the frame, and

means connecting the air pump to the manifolds for Square inchessupplying air under pressure to said manifolds.

Claims

1. A trailer for pulverizing crusty and/or icy snow cover comprising a frame, spaced parallel skis on which the frame is supported, means on the trailer frame for connecting it to a tractor for movement of the ski-supported trailer on the snow cover, a drum mounted on the frame rotatable about an axis transverse to the skis, flails on the drum comprising elongate flexible elements attached at one end to the surface of the drum for rotation therewith, adjustable means mounting the skis to the frame such as to enable moving the skis and frame relative to each other to raise and lower the drum relative to the cover on which the skis rest, said drum normally being held by adjustment of the skis and frame relative to each other at a level above and spaced from the cover such that only the distal ends of the flails, while travelling in a circle about the axis of the drum, engage the cover as they travel between the lower side of the drum and the surface of the cover, said adjustable means comprising pairs of arms, one pair for each ski, means pivotally connecting one end of each pair of arms to the frame, means fixed to the skis pivotally connecting the other end of one of the arms of each pair to the skis, means slidable along the skis in relation to the means fixed thereto pivotally connecting the other ends of the other arms of each pair of arms to the skis, screws connecting the midportions of the arms of each pair of arms, said screws being rotatable to spread or contract the arms relative to each other to raise and lower the frame with respect to the skis, and means for at times effecting rotation of the screws to lower the drum to a position adjacent the cover such as to engage the portions of the flails extending from the drum to their distal ends between the lower surface of the drum and the cover as they travel therebetween.

2. Apparatus according to claim 1, wherein the last-named means are motors connected to the screws.

13. Apparatus according to claim 12, wherein said means for ejecting air under pressure from the tread surfaces of the skis comprise holes through said skis, the lower ends of which are in communication with the tread surfaces thereof, manifolds fixed to the upper sides of the skis with which the upper ends of the holes are in communication, an air pump on the frame, and means connecting the air pump to the manifolds for supplying air under pressure to said manifolds.

14. Apparatus according to claim 13, wherein a pressure of approximately 4 psi is maintained in said manifold for skis having tread surfaces of approximately 960 square inches.