AUTOMATIC LEVELING SYSTEM FOR BLAST HOLE DRILLS AND THE LIKE

• US 3,625,483 A
• Filed: 02/24/1970
• Issued: 12/07/1971
• Est. Priority Date: 02/24/1970
• Status: Expired due to Term

• Current Assignee: Becor Western, Inc. (Caterpillar Incorporated)
• Original Assignee: Thomas A. Stoner
• Inventors: Stoner, Thomas A.
• Primary Examiner(s): Riordon, Robert C.
• Assistant Examiner(s): Melton, David R.
• Application Number:
  US05/013,689
• Time in Patent Office: 651 Days
• Field of Search: 254/86H,89H 280/6R,6H,6.1,6.11 212/145
• US Class Current: 254/423
• CPC Class Codes: B60S 9/12 of telescopic type
• CPC Class Codes: E02F 9/085 Ground-engaging fitting for supporting the machines while working, e.g. outriggers, legs for vehicles in general B60S9/00, for cranes B66C23/78
• CPC Class Codes: E02F 9/22 Hydraulic or pneumatic drives for dipper or bucket arm position control E02F3/43, for blade position control for graders E02F3/844; for turntables E02F9/121; for fork-lift trucks B66F9/22

Abstract

An automatic system for leveling a blast hole drill during raising and lowering includes a front jack on the longitudinal axis of the machine and a pair of rear jacks which straddle the longitudinal axis and define a transverse axis. An operating fluid line for the jacks is connected to a first proportioning valve which is controlled by a first level sensor operative along the longitudinal axis. The proportioning valve apportions flow between the front jack and the two rear jacks and alters the flow ratio as necessary to keep the machine level on the longitudinal axis. A second proportioning valve controlled by a second level sensor operative along the transverse axis is interposed in that output of the first valve which leads toward the two rear jacks. It apportions the flow between the two rear jacks to level the machine along the transverse axis. This sequential apportioning of fluid flow is used to level the machine and keep it level as it is raised and lowered to and from a working position in which it is supported by the jacks.

Claims

1. In a leveling system for a blast hole drill or the like having a base plane, the combination comprising:

a first and a second jack means which are spaced from one another and together define a first axis in the base plane, the second jack means comprising a pair of spaced jacks defining a second axis in the base plane that is generally transverse to the first axis;

a fluid supply line;

a first proportioning valve in the supply line which has a first output leading to the first jack means and a second output leading toward the second jack means, said first proportioning valve being operable to continuously apportion the flow of fluid to the first and second jack means to maintain the base plane level along said first axis;

a first level sensor means adapted to continuously detect the attitude of the base plane along the first axis and operate the first proportioning valve in proportional response thereto;

a second proportioning valve connected to the second output of the first proportioning valve, said second proportioning valve having two outputs leading to respective members of the second jack means and being operable to continuously apportion the flow of fluid to the two jacks to maintain the base plane level along the second axis; and

a second level sensor means adapted to continuously detect the attitude of the base plane along the second axis and operate the second proportioning valve in proportional response thereto.

2. The combination of claim 1 wherein both proportioning valves have normal positions which are assumed when the base plane is level and said proportioning valves can be actuated in either direction from said normal position;

and the ratio of flow through the first and second outputs of the first proportioning valve when it is in normal position is approximateLy equal to the ratio of the piston area of the first jack means to the total piston area of the jacks of the second jack means; and

the ratio of flow through said outputs of the second proportioning valve when it is in normal position is approximately equal to the ratio of the respective piston areas of the jacks of the second jack means.

3. The combination of claim 2 wherein the proportioning valves are adapted to control the flow ratio of fluid moving through them in either direction;

and the sensors are adapted to generate signals corresponding in polarity and magnitude to the attitude of the base plane along their respective axes; and

there is a first set of connections between each sensor and the associated proportioning valve which is used during a raising action; and

there is a second set of connections between each sensor and the associated proportioning valve which is used during a lowering action and in which the polarity of the signal to the valve is reversed; and

there is switch means to select which set of connections is to be used.

4. The combination of claim 3 wherein there are three pressure-sensing devices, one associated with the first output of the first proportioning valve and the other two associated, respectively, with the first and second outputs of the second proportioning valve, each device being adapted to be actuated upon the occurrence of a predetermined low pressure in its associated output which indicates that the associated jack or jack means is no longer supporting a substantial load during a lowering cycle;

and there is an operating circuit between each level sensor unit and its associated proportioning valve; and

each proportioning valve has a self-centering action so that upon an interruption in its operating circuit it will return to centered position; and

there is a first cutoff circuit in the operating circuit for the first proportioning valve which comprises a parallel combination of two normally closed switches, one adapted to be opened upon actuation of one of said other two devices and the other adapted to be opened upon actuation of the other of said other two devices, said combination being connected in series with a third normally closed switch adapted to be opened upon actuation of said one device; and

there is a second cutoff circuit in the operating circuit for the second proportioning valve which comprises a normally closed switch adapted to be opened upon actuation of one of said other two devices and connected in series with another normally closed switch which is adapted to be opened upon actuation of the other of said other two devices; and

each cutoff circuit includes means to deactivate the same during a raising cycle.

5. The combination of claim 4 wherein each of the three pressure-sensing devices is also adapted to be actuated when a preselected percentage of the total weight of the drill is supported by its associated jack or jack means;

and there is a shutoff circuit which is adapted to terminate fluid flow through said fluid supply line, the shutoff circuit including three normally open switches connected in series, each switch being adapted to be closed upon actuation of a respective device, and a time delay means which, upon closing of all three switches causes flow to be terminated after a predetermined time interval.