US2304524A

US2304524A - Control for shovels

Info

Publication number: US2304524A
Application number: US369654A
Authority: US
Inventors: Roy H Zeilman
Original assignee: Thew Shovel Co
Current assignee: Thew Shovel Co
Priority date: 1940-12-11
Filing date: 1940-12-11
Publication date: 1942-12-08
Anticipated expiration: 1959-12-08

Description

8, 1942- R. H. ZEILMAN CONTROL FOR SHOVELS Filed Dec. 11, 1940 2 Sheets-Sheet 1 IIIVVENTOR. BY illmw Patented Dec. 8, 1942 UNiTED ST TES ares! v reins CONTROL FOR SHOVELS Roy H. Zeilman, Lorain. Ohio, assignor to Thew =Shovel Company, Lorain, Ohio, a corporation of Ohio Claims.

My invention relates to power shovels and relates more particularly to improvements and simplification in controls for such shovels.

Power shovels of the type to which my invention pertains comprise a rotatable superstructure carrying a boom and adapted to revolve upon a crawler body member. The boom, in turn, carries a dipper stick and dipper, or shovel. Controls for such power shovels usually comprise hand levers and foot brakes for controlling the various operations, such as driving the cable hoist for the shovel, rotating the superstructure, crowding and retracting the dipper stick in shovel operation, propelling the crawler in either for- Ward or backward direction, and hoisting and lowering the boom.

A fundamental object of my invention i to provide such improved controls for power shovels as to enable the operator to more efiiciently and easily operate the various controls.

' Another object of my invention is to provide an improved swing lever and crowd brake control.

Other objects of my invention and the invention itself will become apparent from a perusal of the following description and drawings, in which:

Fig. 1 is a side view of a complete shovel embodying my invention and'showing the arrangement of the entire mechanism, somewhat simplified, whereby the cooperative relationship of the parts is illustrated;

Fig. 2 is a view of the controls for the power shovel of my invention showing the arrangement of said controls as viewed from the oper-- ators position;

Fig. 3 is an enlarged view of the crowd brake of my invention showing the brak in its off position and embodying a sectional view of the valve control for said crowd brake; and

Fig. 4 is a view similar to Fig. 3 but showing the valve and the cylinder in different operative position or in brake on position.

Referring now to the drawings in all of which like parts are designated by like reference characters, the principal parts of the shovel are the crawler body 2 upon which is rotatably mounted the driving assembly generally indicated by reference numeral l and carrying the boom 3 which, in turn, carries the dipper i by means of the dipper stick 5 supported at its dipper end by a suitable tackle, these parts and their general arrangement being well known in the art.

The boom 3 is pivotally connected as at 6 to the front end of the floor of the driving assembly I and is supported by suspension cables I and may be raised or lowered thereby, by mechanism not shown. The dipper stick 5 is provided with rack teeth 8 which engage pinion teeth 53 on a shipper shaft iii mounted transversely on the boom and included in and controlled by the usual type of chain crowd mechanism for outwardly projecting the dipper stick and the shovel or dipper connected thereto and for retracting the same. This mechanism will be later more fully described.

Power for the various operations may be obtained from an engine, illustrated at 2B, and be transmitted by a chain 25 to a main drive pinion 22. This pinion constantly drives three gears 23,

24 and 25 which may be selectively clutched to or disengaged from the mechanisms for swinging, crowding or travelling, and hoisting, respectively. Gear 23 drives the swinging mechanism 26, such drive being under the control of the left-hand lever 21 at the operators station, Fig. 2, through linkages and clutches, not shown. Gear 25 drives the drum 28 for the hoisting cable 29 of the shovel 4, this drive being similarly under the control of the right-hand lever 30 at the operators station, and also of the brake pedal 3i at his right foot.

The crowding mechanism for the dipper stick 5 is also driven from the main drive pinion 22. The gear 24, previously mentioned as constantly driven by this pinion is selectively clutched, through operators centrally disposed hand lever M3 and linkages and clutches not shown, with a chain sprocket M. A chain 42 passes around this sprocket and a first sprocket 43 pivoted at the hinge point B of the boom 3. A second sprocket, rigid with the first, drives a chain 44 which, in turn, drives the pinion 9 on the shipper shaft it.

A brake is provided to retain the dipper stick in its crowded position, against the pull of the hoist cable 29. As illustrated in Figs. 1, 3 and 4, a brake band 4-5 passes over a drum 46, which is secured to the sprocket it. One end of this band is fixedly secured to the main frame, as at 41, while the other end is carried by an arm 48 secured to a rockshaft 49. A second and longer arm 50, also secured to the rockshaft, is adapted to be moved by the piston 51 of an operating cylinder 52 pivoted to the main frame at 54. A spring 53 within the cylinder normally urges the piston to brake-releasing position.

The brake cylinder may be operated by means of vacuum and air pressure, a suitable system being illustrated in Figs. 3 and 4, under the control of a thumb lever 6!], carried by the operators swing lever 2'], as illustrated in Figs. 1 and 2. The system comprises a vacuum tank 6!, an air tank 62, a vacuum pump 63, and a valve 64 which selectively places the brake cylinder in communication with either the air line or the vacuum line. The pump 53 may conveniently be placed near the engine and be driven directly by it, as illustrated in Fig. 1. The pump exhausts air from the vacuum tank into the air tank and maintains the latter at a pressure a few pounds above atmospheric. The vacuum may be applied to both sides of the piston 5| or only to one side and compressed air to the other. The first application is that shown in Fig. 3 where it will be seen that the plunger 65 of the valve 64 is in its lowermost position, opening the chamber 65 of the cylinder, through the line 61, to the vacuum line 58. The other chamber 69 is in constant communication, through line It, with the same vacuum line 68 and hence the piston is in balanced condition and the spring 53 is free to move it in brakereleasing direction. This is th normal condition of the system, the valve plunger 65 being retained in lowermost position by a compression spring I I.

To apply the crowd brake, the valve plunger 65 is raised to the upper position, illustrated in Fig. 4, allowing compressed air from the tank 62 to enter the chamber 55, through the line 61'. Since the opposite chamber 69 is still under vacuum, the piston is forcibly moved in brake-applying direction, against the comparatively light force of the spring 53. The lever 50 is thus rocked about its pivot 4d and the brake band is tightened about the drum 46.

The plunger 65 is raised by means of the thumb lever 60 before mentioned. This lever is pivoted at B0 on the swing lever 2! and is in the nature of a bell crank, the longer arm of which extends upwardly to a point conveniently near the operators thumb as he grasps the knob of the swing lever, and the shorter arm of which is linked to the valve plunger by a rod 8 I. It has been found convenient to provide an adjustable compression spring 82, opposing the relatively inaccessible valve spring H, at a point near the thumb lever. Such spring may be interposed between a fixed rod guide 83 on the swing lever and a collar 84 threaded on the rod, thus allowing the thumb pressure, necessary to operate the valve, to be adjusted.

It is to be noted that in mounting the crowd brake upon the swing lever a very convenient and simple arrangement is had. The right hand of the operator is free to operate the crowd lever or the hoist lever as occasion demands, his right foot is used to operate the hoist brake pedal and his left foot is free to rest on a brace 85 or the like, thereby steadying the operator in his position on the seat 86, Fig. 1.

The operator of a power shovel finds the swing lever a very vital factor in his control of the entire cycle since he does his spotting with it, that is, the machine must first be swung so as to locate the shovel or dipper accurately in position for digging and then swing to an accurate dumping position. He habitually keeps his hand upon the swing lever throughout the cycle and therefore, in the present embodiment of this invention, he'needs but to extend his thumb and press the valve control when the crowd brake is to be applied. Thus, one control has been eliminated as far as the labor and energy of the operator is concerned since it is the movements calling on the large muscles which are fatiguing, and in the past a separate crowd brake lever or foot pedal has been necessary.

It is to be understood that, while the foregoing description has been of an embodiment in which a crowd brake control is mounted on a swing control lever and the advantages of the particular combination have been referred to, I do not wish to be limited thereto since similar arrangements can be made with other controls, and comparable advantages gained thereby, within the teachings and scope of this invention.

I claim:

1. In a crowd brake control, a swing lever, a thumb lever mounted upon said swing lever, valve means associated with said thumb lever, said valve having inlet ports communicating with a vacuum tank and an air tank, and an outlet port communicating with a brake cylinder, said brake cylinder having further communication with said vacuum tank, a crowd brake securely mounted upon a main frame and having linkage means disposed between said brake and said brake cylinder, said means adapted to be secured to piston plunger means disposed within said brake cylinder whereby both of the chambers provided in the brake cylinder are opened to the vacuum line and the piston is in balanced condition, spring means disposed within the cylinder normally urging the piston to brake-releasing position.

2. In a crowd brake control, a swing lever, a thumb lever mounted upon said swing lever, valve means associated with said thumb lever, said valve having inlet ports communicating with a vacuum tank and an air tank, and an outlet port communicating with a brake cylinder, said brake cylinder having further communication with said vacuum tank, a crowd brake securely mounted upon a main frame and having linkage means disposed between said brake and said brake cylinder, said means adapted to be secured to piston plunger means disposed within said brake cylinder whereby, when manual pressure is exerted upon said thumb lever, compressed air from said air tank enters an upper chamber of the brake cylinder and a lower chamber of said cylinder being under vacuum pressure, piston means are forcibly moved in brake applying direction against the force of a piston resisting spring disposed within said cylinder to apply the crowd brake.

3. In a crowd brake control, a manually operable control swing lever having a control mounted thereon, valve means associated therewith, a valve plunger, said valve means being linked to said control and said plunger being moved up wardly or downwardly by the raising or lowering of said control by the release or application of manual pressure on the control, said valve means having a pair of inlet ports, said ports communicating with a vacuum tank and an air tank, and an outlet port communicating with a brake cylinder, said brake cylinder having further communication with said vacuum tank, a crowd brake securely mounted upon a main frame and having linkage means disposed between said brake and said brake cylinder, said linkage means adapted to be secured to piston plunger means disposed within said brake cylinder whereby both of the chambers provided in the brake cylinder are opened to the vacuum line and the piston is in balanced condition, spring means disposed within the cylinder normally urging the piston to brakereleasing position.

4. In a crowd brake control, a manually operable control swing lever having a control mounted thereon, valve means associated therewith, said valve means comprising a valve plunger linked with said control whereby said plunger is directly responsive to raising or lowering of the control whereby a pair of inlet ports communicate with a brake cylinder to operate the same, said brake cylinder having further communication with said vacuum tank, a crowd brake securely mounted upon a main frame and having linkage means disposed between said brake and said brake cylinder, said linkage means adapted to be secured to piston plunger means disposed within said brake cylinder, said brake cylinder adapted to have one of its chambers open to the vacuum line and the other of its chambers open to the air line whereby an unbalanced condition is produced in the cylinder and the piston is urged downwardly in the cylinder thus applying the brake.

5.. In controls for power shovels consisting of a swing lever, a crowd lever, a hoist lever and a hoist brake, the combination of a swing lever and crowd brake control, said crowd brake control being mounted upon said swing lever, said swing lever and said control adapted to be manually operatedland by the same manual means by the operator, valve means associated with the crowd brake and crowd brake control, said valve means being caused by said manual means to exert pressure upon the brake to apply braking action uponthe crowd, the release of said valve means releasingv said braking effort.

ROY H. ZEILMAN.