US2788578A - Surveyor's target staff support - Google Patents

Description

April 16, 1957 s. 'DIGIACINTO SURVEYORS TARGET STAFF SUPPORT Filed June 25, 1956 SURVEYORS TARGET STAFF SUPPORT Sam Digiacinto, Bellflower, Calif.

Application June 25, 1956, Serial No. 593,642

3 Claims. (CI. 33-74) This invention relates to a surveyors target staff and more particularly to an improved self-supporting staff provided with easily adjusted means for aligning the target thereof directly above a known reference point with accuracy and certainty.

In the exacting art of surveying it is imperative that measurements be made with great preciseness, an objective dependent in considerable degree on the accurate alignment of the target with the reference point. While a primary duty of the crewman in charge of the target staff is vigilance in assuring this objective by holding the staff properly, variable results have been commonplace and diflicult to detect.

A principal object of the present invention is to obviate these and other disadvantages by providing a self-supporting target staff so constructed that the target can be aligned accurately with a reference point. Additionally, and of particular importance, is the fact that the selfsupporting target staff of this invention is easily and quickly adjustable to align the target vertically with respect to the reference point and to retain the target so aligned while the survey party obtains readings. Immediately thereafter and prior to moving the target staff to a new location, the surveyor has an opportunity to check the position of the target to make certain that it has remained in the desired position. In this manner the displacement of the staff is detected at once, an operation obviously not possible when the target is manually supported.

These and other more specific objects will appear upon reading the specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

Figure l is a perspective view of a surveyors target staff incorporating the present invention properly centered over a reference point and facing the remotely located surveying instrument;

Figure 2 is a transverse sectional view taken on a horizontal plane as indicated by line 22 on Figure 1;

Figure 3 is an enlarged elevational view partly in section of the surveyors staff;

Figure 4 is a longitudinal sectional view taken along line 4-4 on Figure 3; and

Figure 5 is an enlarged detail view in section through one of the adjustable legs.

The improved surveyors staff designated generally comprises a heavy metal base 11 having an upwardly opening tubular socket member 12 secured to one longitudinal edge as by welding 13. Threadedly supported in the side wall of socket 12 are one or more thumb screws l4, 14 the inner ends of which are engageable with the lower end of a conventional surveyors target staff 15 seated in socket 12 to anchor the staff firmly in place and having a sighting target 17 secured to its upper end.

Suspended by a light cord 21 from a pin 22 secured nited States Patent 0 2,788,578 Patented Apr. 16, p 1957 to the target along its vertical center line is a plumb bob 23 having its pointed lower end terminating somewhat below the lower surface of the staff-supporting base 11 as is clearly indicated in Figures 3 and 4. Base 11 is preferably weighted at its corners as by heavy metal blocks 30 as an aid in preventing the overturning of the stafi by the wind. Owing to the location of staff 15 audits supporting socket 12 near one longitudinal edge of base 11 it will be apparent that plumb bob 23 is suspended closely beside but spaced from the edge of the base. To facilitate the alignment of the bob with. the center of a reference point 24 on the ground, base 11 is provided with three adjustable supporting legs 25 comprising threaded T-shaped members having thumb pieces 26 at their upper ends and extending through threaded bores 27 disposed as indicated in Figure 2. The spherically shaped lower end 28 of legs 25 seat loosely in a similarly shaped socket of a pad 29 providing a suitable wide area base for the legs.

In operation, the surveyor first sets up the self-supporting staff 10 with target 17 facing toward surveying instrument 20. Plumb bob 23 is suspended from support 22 on the target by means of a cord having a slipknot so that the bob can be conveniently adjusted to a position spaced slightly above the ground reference point 24. Thereafter, legs 25 are adjusted by the aid of thumb pieces 26 to position the plumb bob in direct alignment with reference point 24, care being exercised that the adjustable leg to the rear of the staff is sufficiently high initially for the plumb bob to hang somewhat forwardly of the edge of base 11. As will be evident from Figure 4, turning leg 25 to the rear of the staff to lower it relative to plate 11 is effective to tilt the upper end of the staff to the left causing the plumb bob to swing somewhat further away from the forward side of the base. Referring to Figure 3, it will be clear that if the plumb bob hangs to the right of reference point 24, a corrective adjustment to the left is effected by turning the left-hand leg 25 upwardly to lower the left end of the base. It will therefore be apparent that the plumb bob can. be quickly and easily brought into vertical alignment with the reference point by appropriate adjustment of the three supporting legs. Once adjustment has been completed, the crewman obtains a reading with full assurance that the target is in accurate vertical alignment with the ground reference point. Upon returning to the reference point to move staff 15 to a new location the surveyor first makes a quick check to determine whether the plumb bob remains properly centered over the reference point. If the wind or some other disturbance has shifted the staff from its intended setting, the surveyor is appraised of this fact by observation of the plumb hob and takes a new reading after correcting the position of the staif.

While the particular self-supporting surveyors target stafi herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. In a surveyors target staff of the type having a target and a plumb bob suspended from the target, that improvement which comprises a supporting base for said staff having means rigid therewith for detachably receiving the lower end of the target staff and supporting the same in an upright position, a plurality of vertically adjustable legs mounted on said base, said legs being adjustable to shift said staff until said plumb bob lies directly over a reference point located closely beside one edge of the supporting base for said staff.

' 2. In a surveyors target staff of the type having a target'and a plumb bob suspended from the target, that improvement which comprises a heavy supporting base for said staff having means adjacent one side edge thereof for supporting a target staif in an upright position with its movable target on the opposite side of the staff from saidbase, said base having three vertically adjustable legs projecting from the lower side thereof, said legs being adjustable to bring said plumb bob into vertical alignment with a ground reference point closely adjacent the lower-end of said target staff and to one side of said base.

'3 A self-supporting surveyors staff comprising an elongated rigid staif having a target and provided with a plumb bob suspended from said target havingits pointed lower end terminating close to the base of. said staff, a heavy supporting base having a socket for rigidly seating 4 said staif and supporting the same in an upright position adjacent one edge of said base, a plurality of adjustable legs carried by said base and adjustable to bring the point of said plumb bob into vertical alignment with a fixed reference point located to one side of said base near the seating socket for said target staff.

References Cited in the file of this patent UNITED STATES PATENTS 147,210 Wederkinch Feb. 3, 1874 2,245,901 Chaskin June 17, 1941 2,575,245 Carlson et al. Nov. 13, 1951 2,729,897 Smith Jan. 10, 1956 FOREIGN PATENTS 23,237 Germany Aug. 7, 1883

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