Abstract:
The civil engineering elevation measuring stick for use in a laser elevation measuring system includes a primary pole with a top end, a bottom end at least four flat side walls. A top end cap, a bottom end cap are attached to the primary pole. A secondary tubular pole telescopically receives the primary pole. Bearings support the secondary tube for sliding movement relative to the primary pole between the top and bottom end caps. A laser beam receiver mounting surface is provided on the secondary tube. A measuring scale is fixed to the primary pole in a location that permits the direct measurement of the deviation between the elevation of a measured surface and desired grade surface.

Description:
The disclosure incorporates the surveyors elevation measuring stick and method disclosed in provisional patent applications 60/270,654 filed Feb. 22, 2001 and 60/277,109 filed Mar. 19, 2001, whose priority is claimed for this application. 
    
    
     TECHNICAL FIELD 
     The surveyors elevation measuring stick is used in combination with a laser beam system to measure the difference between the actual elevation and the desired elevation at any given location. 
     BACKGROUND OF THE INVENTION 
     Earth moving equipment is used to move soil and excavate for civil engineering projects. An underground pipe laid in a ditch to carry liquids conveyed by gravity must have a uniform and constant change in elevation. If the pipe has portions that are lower than planned and portions that are higher than planned, liquid will be held in the low spots and solids will settle out of the liquid in these low areas. Over a period of time, the capacity of the pipe will be decreased and the pipe may even become plugged. 
     A building foundation must be level or at least have level sections and steps with a known elevation change. If the foundation is not level, building walls are unlikely to be vertical. Building walls that are not vertical are generally weaker than planned and could overtime collapse. 
     Roads and airport runways are generally not level. However they must have sections with a uniform change in elevation. They may also have side slopes in a direction transverse to the direction of vehicle traffic to carry water away. High areas and low areas can hold water and force vehicles to reduce speed. High spots in low areas on a runway can render a runway unusable for high speed aircraft. Such areas can also increase loads on aircraft structures and reduce the useful life of aircraft. 
     The above examples relate to structures that require careful measurement of elevation during construction. Many more examples could be given. 
     Civil engineers and others have used a transit and a measuring stick to measure and calculate elevations at selected positions. These devices have required skilled individuals and meticulous records to avoid mistakes in measuring and in calculating results. 
     Lasers are available today to assist in determining elevations. Such devices can improve the accuracy and speed up the measuring process. However, the measuring stick generally has a graduated scale that starts at the surface and extends upward. When using a laser and a measuring device, the actual elevation at a given point is measured. Then we determine what the elevation should be. Finally the deviation from the desired elevation is calculated. Once the deviation is known, the information is given to a machine operator and he can make required changes. These changes are usually made by removing or adding materials such as rock and soil. 
     The measuring procedure takes time. While measurements are taken, calculations are made and the results are relayed to a machine operator, the operator and an expensive earth moving machine are frequently idle. This idle time can be very expensive. 
     Mistakes are frequently made when calculating the results of a elevation measurement. In some cases one measurement is subtracted from another measurement or calculation. In other cases a measurement is added to another measurement or calculation. It is easy to add when you should have subtracted it is also easy to make errors when adding or subtracting measurements that are to the nearest sixteenth of an inch. Making such calculations is, as mentioned above, time consuming. 
     SUMMARY OF THE INVENTION 
     The civil engineering elevation measuring stick is for use in a laser beam measuring system. The measuring stick includes a primary pole with a top end and a bottom end. A secondary tube telescopically receives the primary pole. The length of the secondary tube from the secondary tube top end to the secondary tube bottom end does not substantially exceed half the length of the primary pole. Four flat secondary walls of the secondary tube extend from the secondary tube bottom end to the secondary tube top end. A pair of spaced apart bottom apertures adjacent to the secondary tube bottom end pass through each of the four flat secondary walls. A pair of spaced apart top apertures adjacent to the secondary tube top end pass through each of the four flat secondary walls. A top ball bearing is positioned in each aperture of the pairs of spaced apart top apertures. A bottom ball bearing is positioned in each aperture of the pairs of bottom ball bearing apertures. Ball bearing retainers hold the top and bottom ball bearings in the apertures. The top and bottom ball bearings prevent contact between inside surfaces of the secondary tube and the primary pole thereby allowing the secondary tube to move freely on the ball bearings between the primary pole top end and the primary pole bottom end. A top end cap and a bottom end cap on the primary pole limit movement of the secondary tube relative to the primary pole. Laser beam receiver mounting surfaces are provided on the secondary tube. At least one measurement scale is provided on the primary pole to measure the distance the secondary tube is moved relative to the primary pole from an index position when a laser beam receiver clamped to the secondary tube is centered on a laser beam. The measured distance indicates the distance a surface supporting the bottom end of the primary pole is above or below the desired elevation thereby indicating how much material is to be removed or how much material is to be added. 
     One version of the measuring stick includes a spring that urges the secondary tube toward the primary pole top end. With this version, the index point from which measurements are taken is at the top of the primary pole. This version is used when excavating and accurately indicates how much material remains to be removed. 
     The other version of the measuring stick has an index point, from which measurements are taken, in the center portion of the primary pole. Two scales are provided on the primary pole. Both scales start at the index point. The upper scale increases as you move up from the index point. The lower scale increases as you move down from the index point. A viewing aperture with a position indicator is provided in a wall of the secondary tube. The upper scale encase the quantity of fill that is required. The lower scale indicates the quantity of material that is to be removed. With this version, a clamp is provided to hold the secondary tube in a fixed position relative to the primary pole while the scales are read. 
     Both versions of the measuring stick measure the deviation from the desired elevation without the need to make calculations. Eliminating calculations in the field saves time and reduces errors. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein: 
     FIG. 1 is an expanded perspective view of the measuring stick; 
     FIG. 2 is an expanded plan view of the measuring stick; 
     FIG. 3A is an elevational view of the measuring stick with the secondary tube against the top end cap and with the index mark at the top end of the primary pole; 
     FIG. 3B is an elevational view similar to FIG. 3A indicating that a relatively small quantity of material remains to be removed; 
     FIG. 3C is an elevational view similar to FIG. 3B indicating that an intermediate quantity of material remains to be removed; 
     FIG. 3D is an elevational view similar to  3 C indicating that a large quantity remains to be removed; 
     FIG. 3E is an elevational view similar to FIG. 3A indicating the total quantity of material to be removed to obtain the desired grade level; 
     FIG. 4 is an expanded perspective view of a modified measuring stick with an index mark on the center of the primary pole; 
     FIG. 5 is an expanded front elevational view of the modified measuring stick; 
     FIG. 6 is an expanded rear elevational view of the modified measuring stick; 
     FIG. 7A is an elevational view of the modified measuring stick at the beginning of a filling operation to raise the level of the surface; 
     FIG. 7B is an elevational view of the modified measuring stick after partial filling; 
     FIG. 7C is an elevational view of the modified measuring stick when substantial filling is required; 
     FIG. 7D is an elevational view of the modified measuring stick when a small quantity of filling is required; and 
     FIG. 7E is an elevational view of the modified measuring stick when additional excavation is required. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The measuring device  10  includes a main pole  12 . The main pole  12  is an elongated square tube. A slot  14  in one wall  16  of the main pole  12  extends from the main tube bottom  18  to about midway between the main tube bottom and the main tube top  20 . 
     A square secondary tube  22  that is about one half the length of the main pole  12  telescopically receives the main pole. The secondary tube  22  has an inside dimension that is somewhat larger than the outside dimensions of the main pole  12 . The secondary tube  22  has side walls  24 ,  26 ,  28  and  30 . Two apertures  32  are bored through each side wall  24 - 30  near the lower tube end  34  in positions adjacent to adjacent side walls and spaced from each other. Two additional apertures  36  are bored through each side wall  24 - 30  near the upper end  38  in positions adjacent to adjacent side walls and spaced from each other. These apertures  32  and  36  are spaced apart and near adjacent side walls to provide space for measurement scales between the ball races on the side walls for the main pole. A bearing ball  40  with a diameter that exceeds the wall thickness of the side walls  24 - 30  is inserted in each of the apertures  32  and  36 . Bearing plates  42  of a molded nylon material are secured to the side walls  24 - 30  of the secondary tube  22 , in positions that cover the apertures  32  and  36 , by screws. The bearing plates  42  load the balls  40  and center the main pole  12  radially within the secondary tube  22 . The bearing plates  42  are connected together in pairs so that two screws secure each pair of connected bearing plates  42  to retain the plates in fixed positions on the secondary tube  22 . The balls  40  act as bearings to guide the secondary tube  22  when it is moved axially relative to the main pole  12 . 
     A top cap  44  is fixed to the top  20  of the main pole  12  by a roll pin  46 . A tension spring  48  has an upper end connected to the top cap  44  and is received within the main pole  12 . The lower end of the spring is connected to a hook  50  that passes through the slot  14  in the wall  16  of the main pole  12  and is bolted to the secondary tube  22 . A bottom cap  52  is secured to the main tube bottom  18  by a roll pin  54 . The top cap  44  and the bottom cap  42  limit axial movement of the secondary tube  22  relative to the main pole  12 . The spring  48  urges the secondary tube  22  toward the top cap  44 . 
     A scale  56  on the side wall  24  of the secondary tube  22  starts at 36 inches near the lower end  34  and extends up to the upper tube end  38  and a seventy one inch mark. When the secondary tube  22  has its upper end  38  in contact with the top cap  44 , the starting mark of 36 inches on the scale  56  is 36 inches from the bottom end of the bottom cap  52 . scale  58  is fixed to the wall  16  of the main pole  12  and extends downward toward the slot  14 . The one inch mark on the scale  58  is one inch from the top cap  44  and an index point. The numbers on the scale  58  increase as you move from the top  20  of the main pole  12  toward the main pole bottom  18 . The scale  58  as shown ends at about 34 inches. 
     The length of the measuring device  10  can be manufactured with increased or decreased length as required to accomplish different measuring tasks. 
     During use of the measuring device  10 , a laser beam receiver is clamped to the secondary tube  22 . Generally the laser beam receiver is clamped to the secondary tube  22  at a height of the beam from a reference surface, where the reference surface is on the desired grade line. If the laser beam generator is for example 41 and ⅛ inches from a reference surface, the beam receiver is clamped to the secondary tube  22  at the 41 and ⅛ inch level. To determine how much material needs to be removed at a selected location, the bottom cap  52  on the main pole  12  is positioned on the surface of the soil that is to be removed with the main pole held in a vertical position. The secondary tube is than lowered manually against the tension of the spring  48  until a beam receiver is centered on the laser beam. The distance the secondary tube  22  is lowered is read on the scale  58  on the main pole  12  while the laser beam is centered on the beam receiver. The distance measured on the scale  58  indicates the depth of the soil or other material that is to be removed at that location. No calculations are required. In many situations, the operator of an excavator or other earth moving machine can observe the position of the secondary tube  22 , from his operator station, when the measurement is taken and proceeds to remove the material without discussions with the person making the measurement. When the person making the measurement does not have to climb out of a trench and climb up onto the excavator to relay information, productivity is improved substantially. 
     The modified measuring device  110  is similar to the measuring device described above. The modified measuring device  110  is employed when the surface that is being shaped is close to the desired grade and some areas need to be raised while other areas need to be lowered. It has a main or primary pole  112  that is an elongated square tube. A square secondary tube  122  that is about one half the length of the main pole  112  telescopically receives the main pole. Bearing plates  142  and bearing bails  140  in apertures  132  permit the secondary tube  122  to slide relative to the main pole  112 . 
     Two measuring tapes  160  and  162  are provided on one wall  116  of the main pole  112 . Both tapes  160  and  162  start at zero in the center  164  of the main pole  112 . Measuring tapes  160  and  162  are also provided on the wall  117  of the main pole  112 . Tape viewing apertures  166  and  168  are provided in walls  124  and  128  of the secondary tube  122 . Each of these apertures  166  and  168  expose the measuring tapes  160  and  162  and are midway between the lower tube end  134  and the upper tube end  138 . A set screw  170 , with a knob  172  for manual rotation of the set screw, screws into the wall  126  of the secondary tube  122 . Tightening the set screw  170  holds the position of the secondary tube  122  relative to the main pole  112 . A Teflon wear strip  174  is mounted between the wall  126  of the tube  122  and the adjacent wall  176  of the pole  112  to prevent set screw  170  from damaging the surface of the pole. The wear strip  174  can be attached to the pole  112  or it can be attached to the inside of the tube  122  and move with the tube. 
     The modified measuring device  110  can use the top and bottom edges of one of the tape viewing apertures  166  or  168  as position indicators or a wire  190  can extend across the center of each of the apertures. If the top and bottom edges of the viewing apertures  166  and  168  are both used, the positions of the measuring scales  160  and  162  will have to be adjusted to accommodate the space between the two edges. When the secondary tube  122  is centered on the main pole  112 , both edges of viewing apertures would have to be on zero start points of the scales  160  and  162 . 
     During use of the modified measuring device  110 , the secondary tube  122  is clamped to the main pole  112  with an indicator  190  in one of the apertures in alignment with the zero mark on both scales  160  and  162 . A laser beam receiver is elevated to a position in which it is centered on a laser beam, when the main pole bottom  118  is supported on a reference surface that is on the desired grade line, and clamped to the secondary tube  122 . The bottom  118  of the main pole  112  is placed on a surface where the elevation is to be measured. If the laser beam receiver is centered on the laser beam the elevation is correct. If the laser beam receiver is lowered together with the secondary tube  122  to be centered on the beam, the scale  162  will indicate directly how much soil remains to be removed. If the laser beam receiver is raised together with the secondary tube  122 , to be centered on the laser beam, the scale  160  will indicate directly how much fill needs to be added. No calculations are required to determine deviations in elevation from the desired elevation. 
     The disclosed embodiments are representative of presently preferred forms of the invention, but are intended to illustrative rather than definitive of. The invention is defined in the claims.