US2997276A - Trench digging machine - Google Patents

Description

1961 c. J. DAVIS 2,997,276

TRENCH DIGGING MACHINE Filed Aug. 7, 1959 2 Sheets-Sheet l INVENTOR CHARLES J DAVIS Aug. 22, 1961 c. J. DAVIS 2,997,276

TRENCH DIGGING MACHINE Filed Aug. 7, 1959 x 2 Sheets-Sheet 2 INVENTOR 442 CHARLES J DAVIS ATTORNEY United States Patent 2,997,276 TRENCH D-IGGING MACHINE Charles J. Davis, 22 Colonial Court, Wichita 8, Kans. Filed Aug. 7, 1959, Ser. No. 832,200 4 Claims. (Cl. 254166) This invention relates to an improved endless chain type trencher or trench digging machine.

It is an important object of the invention to provide a small, portable, simply constructed winch line propelled machine as opposed to large gear drive propelled machines.

It is another object to provide a trencher which does not require a skilled operator because it is self-guided by means of its winch line or cable. It therefore requires only the proper placing of cable guide stakes along the desired path of travel, or the re-locating of the winch line anchor from time to time in order to dig a trench along the exact path desired.

It is an additional object to provide a trencher of the type mentioned in which the winch drum is rotated by a ratchet wheel and lever mechanism rather than by gears. Such mechanism can be set to propel the trencher along the ground at any selected one of a number of different speeds. The machine can thus adapt itself to various digging conditions, such as ground hardness variations, ground moisture variations, depth and width of trench being dug, etc.

Additional objects are to provide a trencher which has a screw type self-locking digging depth control which permits a change in digging depth while the machine is in operation; which is capable of digging a trench around fixed objects or obstacles without attention from the operator, thus leaving the operator free for other tasks; which lays the earth dug in a neat windrow along one side of the trench, making the backfill job easy; and which is so constructed that the endless chain type digging unit can be raised to a position above ground level to permit the entire trencher to be easily moved manually from place to place.

The invention, together with other objects, will be more clearly understood when the following description is read in connection with the accompanying drawings, in which:

FIG. 1 is a side elevation of a trench digging machine embodying my invention;

FIG. 2 is a top plan view of the machine;-

FIG. 3 is a perspective view of a cable slide which constitutes a part of the guiding mechanism for the machine;

FIG. 4 is a fragmentary perspective view with parts in phantom, and illustrates the ratchet wheel and winch driving mechanism of the machine;

FIG. 5 is a side view of a latch for locking the combination directional guide and handle for the machine in an elevated position;

FIG. 6 is a side elevation, with parts in section, of the mechanism for adjusting the depth of the trench to be dug by the digging unit; and

FIGS. 7 and 8 are schematic views of the ratchet wheel drive mechanism for propelling the machine along the ground.

Referring to the drawings my trencher includes a chassis having a rigid frame designated as a whole by the numeral 1% and preferably made of heavy steel plates welded together. The trencher has two wheels 11 and 12 journaled at the forward end of the frame, and a single trailing wheel 13 at the aft end.

A winch drum shaft 14 is journaled transversely near the forward end of the frame. A driven shaft 15 is journaled transversely near the aft end of the frame.

A power unit 16, here illustrated as a gasoline engine, is connected to drive the driven shaft 15 through a conventional, geared speed-reducing transmission 17. The unit is so constructed, however, that an electrical motor can be interchanged with the gasoline engine for driving the entire unit.

An endless chain type trench digging unit is designated as a whole by the numeral 18. It includes a rigid boom 19 which journals sprocket 20 at its outer end. An endless chain 22 is carried by sprocket 20 and sprocket 21, the latter being keyed on drive 15. The chain carries earth-cutting knives 23.

As a means of supporting the digging unit on the chassis '10 the boom is adjustably connected near its inner end, by means of bolts 24 and 25, to one arm of a bell-crank lever 26. This lever is journaled for free rotation about driven shaft 15 by means of a heavy bearing 27 (FIG. 5).

The other arm of the bell crank lever 26 is pivotally connected to one end of an internally threaded rigid link 28, the other end of which receives a similarly threaded screw 29. The other end of screw 29 is journaled in bearings 30 and 31 in the frame 10. The journaled end of screw 29 is keyed to a crank 32. By means of this crank the boom 19 and the entire earth-digging unit can be moved pivotally about the driven shaft 15 between the solid line position shown in FIG. 1 and the dotted line position '33. An auger blade (FIG. 2), designated as awhole by the numeral 63 is fixed on one end of drive shaft 15 immediately adjacent the digging unit chain 22, and serves to move the earth dug by the unit slightly to one side, and to deposit it in a neat windrow alongside the trench being dug.

As previously mentioned my trencher is propelled slow- .ly along the ground as the trench is dug by means of a winch line or cable 34. One end of the cable is attached to a stake or ground anchor (not shown) and the other end of the line is attached to a winch drum 35 (FIG. 2) which is carried by and rotateswith the shaft 14. At its forward end my trencheris equipped with a combination directional guide and handle 36 for the machine. The guide 36' is generally U-shaped and its free ends are pivotally mounted on the front end of the frame 10. When the trencher is in operation the guide 36 is lowered to the position shown in FIG. 1 and cable 34 extends through a slide 37 carried by the forward end of the guide member. The slide 37 is shown in detail in FIG. 3.

When the machine is to be moved from one location to another, the cable 34 is reeled on to the drum and the guide member or handle 36 is raised to the dotted line position 38, FIG. 1. A pair of latches 39 (FIG. 5) are pivotally mounted on the front end of the frame 10 on a common axis 40 and engage a transversely projecting pin 41 on each leg of the handle 36 to lock the handle in the elevated position.

As a means of slowly rotating winch drum 35 to reel in cable 34 to pull the trencher along the ground, a ratchet wheel and lever mechanism is used. This mechanism is clearly shown in FIG. 4, and its operation is illustrated in FIGS. 7 and 8.

The mechanism includes a ratchet wheel 42 which is keyed on shaft 14 to force rotation of that shaft as the ratchet wheel is rotated. A cam lever 43 has one of its ends journaled for free oscillation on the winch shaft 14, and its free end extends radially outward in a plane common to the plane of a cam 44 which is keyed on driven shaft 15. As shaft 15 rotates the cam 44 forces oscillation of lever 43. Intermediate its ends lever 43 carries a ratchet pawl- 45 which is pivotally mounted thereon by means of a pin 46. Pawl 45 also carries a pin 47 the purpose of which will be explained.

A holding pawl 45 is pivotally mounted on a fixed pin 49 supported on the frame 10. Pawl 48 also carries a pin 50. Movement of the two pawls is coordinated by means of a link 51 one end of which is pivotally connected to pawl 48 by the pin 50, and the other end of which is slidably connected to pawl by means of an elongated slot 52 through which the pivot pin 47 extends. A tension spring 53 has its opposite ends connected to the pawl carried pins and 47, respectively, and urges the pointed ends of each of these pawls into contact with the teeth of the ratchet wheel 42. An additional spring 54 has one end connected to the pin 46 and its opposite end connected to a pin 55 mounted on the frame 10. Spring 54 combines with the force of gravity to urge the outer end of the lever 43 downward. The pawl 45, of course, serves to rotate the ratchet wheel 42 a limited distance each time the cam lever 43 is moved upward by the cam 44, while the pawl 48 serves to prevent reverse movement of the ratchet wheel.

As a means of limiting the downward movement of the outer end of the cam lever 43, a hand-operated bell crank lever 56 is journaled for free oscillation on the shaft 14. The journal is a loose fit to permit slight movement of the bell crank out of a plane perpendicular to shaft 14, the purpose of which will be explained. The shape of this lever is more clearly shown in FIG. 4. The handle portion of the bell crank lever 56 carries a fixed detent 57 which engages teeth on a fixed quadrant 58, supported on the frame 10, which quadrant serves to maintain the lever 56 in any desired position with relation to the cam lever 43. By moving lever 56 slightly out of its normal plane perpendicular to shaft 14, its handle may be easily moved to various positions on the quadrant. The offset end 59 (FIG. 4) of bell crank lever 56 extends transversely into the plane of oscillation of the cam lever 43. Thus when bell crank lever 56 is placed in the position shown in FIG. 7 the offset 59 prevents cam lever 43 from moving further downward after the two are in contact. This limits the number of teeth traversed by pawl 45 as lever 43 moves downward, and consequently determines the number of degrees through which the ratchet wheel 42 is moved during each oscillation of the cam lever 43. This, in turn, determines the speed at which the cable 34 is wound on to the drum 35, and thus determines the speed at which the entire trencher moves along the ground and digs its trench.

The bell crank lever 56 serves an additional purpose, as clearly illustrated in FIG. 8. When lever 56 is moved to the position shown in FIG. 8, the offset 59 forces the cam lever 43 to move upward well outside the operational radius of the cam 44. During the latter part of such upward movement the pin 46 contacts the inner end of slot 52 in the link 51. Further upward movement of the cam lever 43 disengages pawl 45 from the teeth of ratchet wheel 42, and transmits a longitudinal movement to the link 51 in the direction of the arrow in FIG. 8. This longitudinal movement of the link is transmitted to the pointed end of pawl 48, and disengages that pawl also from the teeth of the ratchet wheel 42. With both pawls out of contact with the ratchet wheel it is possible for the wheel and shaft 14 to be freely rotated in either direction so that the cable can be manually reeled in or reeled off of drum 35.

This manual rotation of the shaft 14 and its drum 35 is accomplished by a hand wheel 60 (FIG. 4), which is keyed to the shaft 14 but has slight longitudinal movement thereon. A back-up washer 61 mounted on shaft 14 serves to compress a coil spring 62 against the hub of hand wheel 60, and the hub in turn transmits this axial force to the hub of the bell crank lever 56. This axial spring force serves to urge the detent 57 on the bell crank lever 56 into contact with the teeth of the quadrant 58.

Operation With the digging unit 18 in the raised position 33, FIG. 1, and the guide or handle 36 also in the raised position 38, the trencher is moved to the location and position where the digging of the trench is to start. The handle latches 39 on the handle are released and the handle is lowered to the position shown in FIG. 1. The ratchet Wheel mechanism is moved to the position shown in FIG. 8 to release the drum 35 for free rotation with the shaft 14, and the cable is reeled oil? the drum 35 and its outer end anchored by a stake driven into the ground or by any other type of ground anchor (not shown), so that the cable extends along the desired path of the trench to be dug. The cable is inserted into the slide 35 through the slot shown (FIG. 3).

The handle of the bell crank lever 56 is then moved to engage the proper detent on the quadrant 58 so that the oscillating movement of the cam lever 43 will cause pawl 45 to traverse 2, 3, 4, 5 or 6 teeth as the cam lever 43 moves downward during its oscillation. The setting will depend on the desired speed at which the trencher is to travel. This movement of the bell crank lever 56 permits the cam lever 43 to move downward and allow the pawls 45 and 48 to engage the teeth of the ratchet wheel 42.

The power unit 16 is started and the chain 22 on the digging unit begins to move. Depth adjusting crank 32 is rotated to lower the digging unit into ground contact. The starting of the engine causes cam 44 to revolve with shaft 15 and to oscillate the cam lever 43. During each oscillation pawl 45 forces the ratchet wheel 42 to move through a limited number of degrees of rotation, thus rotating shaft 14 and its drum 35. The trencher is thus moved a very slight distance along the ground toward the ground anchor during each oscillation of cam lever 43. The crank 32 is further adjusted as the digging unit 18 digs into the ground until the proper depth of cut is attained. Thereafter the operator is not required to pay any particular attention to the trencher. It will continue its travel along the cable 34 and toward the ground anchor. The speed of the unit can be adjusted while it is in motion by simply changing the position of the bell crank lever 56.

When the unit has traveled the entire distance to the ground anchor and the cable 34 has been reeled in on the drum 35, the ground anchor is re-located and the cable unwound and again anchored to continue the digging of the trench. If it is desired that the trencher follow an irregular path around a fixed object in the ground it is only necessary to drive stakes along the desired path. The unit will follow that cable path, knocking the ground stakes down as it goes.

Having described the invention with sufficient clarity to enable those familiar with this art to construct and use it, I claim:

1. A winch propelled machine comprising: a wheeled chassis including a rigid frame; a winch drum shaft journaled transversely in the frame; a driven shaft also jour naled transversely in the frame alongside but spaced from the drum shaft; a cam fixed on the driven shaft; a ratchet wheel fixed on the drum shaft; a pivotally mounted cam oscillated lever; a ratchet pawl carried by the lever for engaging the ratchet Wheel teeth to partially rotate the ratchet wheel and the drum shaft each time the lever is oscillated by the cam; adjustable limiting means cooperating with said cam lever to selectively determine the extent of movement of the cam lever during each revolution of said cam; a holding pawl pivotally mounted on said frame for engagement with the ratchet teeth to prevent reverse movement of the ratchet wheel; a link connecting said pawls, said link being slidably connected to at least one of said pawls, said slidable connection providing lost motion between said link and at least one of said pawls whereby throughout the extent of said lost motion connection both of said pawls engage said ratchet wheel during oscillation of said cam lever by said cam, and means for moving the adjustable limiting means to a position in which both pawls are out of engagement with said ratchet wheel; a winch drum fixed on the drum shaft; and a cable on the drum, its free end connectible to a ground anchor to pull the entire chassis along the ground toward the anchor as the drum shaft is rotated.

2. The machine described in claim 1 and a rigid guide extending longitudinally forward from the front end of the chassis, and including a cable slide at its forward end in substantial fore and aft alignment with the winch drum, and through which the anchored cable is reeled onto the drum to guide the path of travel of the chassis.

3. The machine described in claim 2 wherein said cable guide comprises a substantially U-shaped member having its free ends pivotally mounted on said frame; and locking means adapted to retain said guide in an elevated position to provide handle means to facilitate moving said machine from one location to another.

4. A winch propelled machine or the like comprising: a wheeled chassis including a rigid frame; a winch drum shaft and a power shaft journaled transversely in said frame and spaced fore and aft therein; a drum carried on and rotatable with the drum shaft; a cam fixed on the power shaft to rotate therewith; a ratchet wheel fixed on the winch shaft; a cam lever having one end journaled on the winch shaft adjacent the ratchet wheel and extending radially outward in the plane of said cam, to be oscillated thereby as the power shaft rotates; a ratchet wheel rotating pawl pivotally mounted on said cam lever in a position to engage the teeth of the ratchet wheel as the lever is oscillated by the cam; a bell crank lever journaled on said winch shaft adjacent to said cam lever and having a portion thereof extending radially outwardly of said shaft and having a portion offset laterally into the plane of said cam lever, means to adjust the position of said bell crank angularly about said shaft to limit selectively the return movement of said cam lever and the driving stroke of said ratchet pawl and thereby determine the rotational speed of the winch shaft, said bell crank lever being adjustable to an intermediate locking position to move said cam lever out of engagement with said cam and thereby stop rotation of said winch shaft; a holding pawl pivotally mounted on said frame for engagement with the ratchet teeth to prevent reverse movement of the ratchet wheel; a link connecting said pawls, said link being slidably connected to at least one of said pawls, said slidable connection providing lost motion between said link and at least one of said pawls of an extent such that both of said pawls are permitted to engage with said ratchet wheel throughout the speed selective and intermediate locking positions of said bell crank lever, said link being effective in another position of said bell crank lever to disengage both of said pawls from said ratchet Wheel and permit free rotation of said drum shaft; and a cable on the winch drum, its free end adapted for connection to a ground anchor to pull the entire machine along the ground toward the anchor as the winch drum shaft is rotated.

References Cited in the file of this patent UNITED STATES PATENTS 1,035,604 Kissel Aug. 13, 1912 1,168,091 Maughmer Jan. 11, 1916 1,484,841 Monahan Feb. 26, 1924 2,302,879 Neighbour et -al Nov. 24, 1942 2,519,075 Schmidt Aug. 15, 1950 2,571,579 Jones Oct. 16, 1951 2,599,741 Bishman et al June 10, 1952 2,714,262 Malzahn Aug. 2, 1955 2,828,557 Brown Apr. 1, 1958 FOREIGN PATENTS 148,796 Australia Oct. 27, 1952

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