WO1999023448A1

WO1999023448A1 - Vehicle ride-height measurement device and method

Info

Publication number: WO1999023448A1
Application number: PCT/US1998/013855
Authority: WO
Inventors: Mark W. Waltz
Original assignee: The Boler Company
Priority date: 1997-11-04
Filing date: 1998-07-02
Publication date: 1999-05-14
Also published as: AU8286398A

Abstract

A ride-height measurement device and method for tractor-trailers measures the elevation from the axis or center point of each of one or more suspension system axles and the bottom surface of its respective trailer subframe or slider, trailer body or tractor frame. The device (10) includes a base (11) and a slide (12) adjustably mounted on the base. An unknown ride-height is measured by placing an elongated top edge (17) of the base flush against the bottom surface of the slider, trailer body or tractor frame. A thumbscrew (23) is loosened to enable slidable adjustment of the slide (12) relative to the base (11), until a bottom edge (47) of the slide contacts the uppermost surface of the axle. An indicator on the base indicates a reading on a selected English (14) or metric scale (15) on the slide, and the measurement then can be preserved if desired by tightening the thumbscrew (23). The device automatically compensates for the vertical distance between the uppermost surface of the axle from which the measurement is taken, and the axis or centre point of the axle. If the measurement differs from the tractor-trailer manufacturer's recommanded ride-height, an adjustment in the ride-height is made. Alternatively, the device can be used to determine if tractor-trailer ride-height is correctly set, by setting the device to the manufacturer's predetermined recommended ride-height measurement, and placing the device between the uppermost surface of the axle and the bottom surface of the slider, trailer body or tractor frame.

Description

VEHICLE RIDE-HEIGHT MEASUREMENT DEVICE AND METHOD

BACKGROUND OF THE INVENTION TECHNICAL FIELD

The invention relates to vehicle ride-height measurement devices and in particular to ride-height measurement devices for tractor- trailers. More particularly, the invention is directed to a device and method which measures the distance between the bottom surface of a tractor-trailer frame and the axis of each of one or more axles.

BACKGROUND ART

Movable subframes, typically referred to as sliders, have been utilized on tractor-trailers or semi-trailers for many years. One or more axle/suspension systems usually are suspended from a single slider structure. The slider is in turn mounted on the underside of the trailer body, and is movable longitudinally therealong to provide a means of variable load distribution. More specifically, the amount of cargo which a trailer may carry is governed by local, state, and/or national road and bridge laws, and is dependent on proper load distribution. The basic principle behind most road and bridge laws is to limit the maximum load that a vehicle may carry, as well as to limit the maximum load that can be supported by individual axles. A trailer having a slider gains an advantage with respect to laws governing maximum axle loads. More particularly, proper placement of the slider varies individual axle loads or redistributes the trailer load so that it is within legal limits. Once properly positioned, the slider is locked in place on the underside of the trailer by a retractable pin mechanism.

Conventional slider designs were developed before the advent of air suspension systems for trailers. At that time, spring suspension systems were the suspension of choice for trailers and sliders. However, the spring suspension system was unable to provide any load distribution for varying load situations, thus creating the need for a slider which alone provided variable load distribution. The development of the slider resulted in good variable load distribution for trailers, which enabled trailers having sliders to carry heavier loads. Moreover, the subsequent development of air suspension systems provided load equalization among multiple axles for tractor- trailers, with or without the utilization of sliders, as well as improved ride quality for individual axles.

In addition to the movable slider axle/suspension systems, one or more fixed axle/suspension systems are also usually suspended directly from the underside of the trailer body and directly from the underside of the tractor frame, and are typically referred to as fixed primary suspensions.

The ride-height of a tractor-trailer generally is considered to be the elevation of the bottom of the slider, trailer body or tractor frame with respect to the axis of each of one or more respective suspension system .axles. The tractor- trailer ride-height is important for several reasons. If the ride-height is too small, the air springs of the suspension system do not operate efficiently and are more susceptible to damage along with other components of the tractor- trailer. Such damage can ultimately result in the transfer of unwanted forces through the vehicle trailer and into the tractor cab, creating a situation called "driver backslap" wherein the driver is jerked forward and backward during operation of the vehicle. Too short a ride-height distance can also result in unwanted forces imparted to any cargo being carried in the trailer, and can cause either shifting of the cargo or undesirable shocks to the cargo. Conversely, if the ride-height is too large, damage is more likely for various components of the axle/suspension system, including the air springs. Shock absorbers of the axle/suspension system are more susceptible to damage due to possible repeated overextension and the cross-members of the subframe can even suffer structural damage from too large a ride-height. Thus, it can be seen that maintaining correct tractor-trailer ride-height can prevent unnecessary axle/suspension system damage and resulting repairs.

Heretofore, ride-heights have been set according to manufacturer specifications, either in the factory during manufacture of the tractor- trailer or by mechanics maintaining a fleet of tractor-trailers, using measurement devices such as simple rulers or tape measures. In the tractor-trailer aftermarket, maintenance shops utilize the same types of measurement devices. Unfortunately, the use of such simple measurement devices to gauge ride-height is subject to human error in both the physical measurement and mathematical calculation of the distance. More specifically, ride-height measurement often is misunderstood, and often is measured from the top of the axle, instead of the axis of the axle, to the bottom of the slider, trailer body or tractor frame. Even when ride-height is measured correctly, it is very difficult to estimate and measure from the exact axis or center point of the axle, and when such attempts are made human error often occurs. Alternatively, for example, since most square or round axles in North America are five inches (5") in diameter, in many cases no attempt even is made to measure directly from the center point of the axle due to the difficulty in estimating the point as described above, but rather the individual will measure from the uppermost surface of the axle to the bottom of the subframe structure, trailer body or tractor frame, and compensate by adding two and one-half inches (2 1/2") to the measurement. Such a technique also often results in human error because mathematical mistakes frequently occur in the addition of the two and one-half inches (2 1/2") to the distance measured from the top of the axle to the bottom surface of the subframe, trailer body or tractor frame, or the addition step is inadvertently skipped altogether.

The present invention solves the problems of inaccurate physical measuring and mathematical errors in determining the distance from the axis or center point of the suspension system axles to the bottom surface of the subframe, trailer body or tractor frame, otherwise known as the tractor- trailer ride-height. The present invention solves the above-described problems through the use of a simple, accurate and reliable adjustable measuring device and method which automatically compensates for the distance from the top of the axle to the center point of the axle when measuring ride-height from the top of the axle.

SUMMARY OF THE INVENTION Objectives of the present invention include providing a ride-height measurement device and method for tractor-trailers, which automatically compensates for the distance from the axis or center point of the axle of a suspension system to the top of the axle, thereby eliminating physical measurement and mathematical calculation errors in measuring the ride-height. Another objective of the present invention is to provide such a ride- height measurement device and method for tractor-trailers, which is easy to use, inexpensive, accurate, and durable.

These objectives and advantages are obtained by a device for determining a distance between at least one point on a first object and at least one point on a second object, wherein the second object point is located a certain distance from a point intermediate the first and second object points, the intermediate point being located on the second object, the device including a base, the base having a first surface for contacting the first object point; and a slide movably mounted on the base, the slide having a second surface for contacting the intermediate point, wherein the device automatically compensates for the distance between the second object point and the intermediate point.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiment of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims.

FIG. 1 is a front elevational view of the ride-height measurement device for tractor-trailers of the present invention, showing in dot-dash lines the manner in which the device can be adjusted when taking a measurement;

FIG. 2 is an exploded perspective view of the ride-height measurement device of FIG. 1;

FIG. 3 is a view showing use of the ride-height measurement device to determine the distance from the axis or center point of an axle to the bottom surface of a tractor-trailer subframe; and

FIG. 4 is a view similar to FIG. 3, but showing the ride-height measurement device set to a predetermined correct ride-height and determining that the distance from the center point of the axle to the bottom surface of the tractor- trailer subframe is too large, and further showing in dot-dash lines the correct position of the axle for proper ride-height. Similar numerals refer to similar parts throughout the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The improved vehicle ride-height measurement device of the present invention is indicated generally at 10 and is shown in FIG. 1. Measurement device

10 includes a base 11 and a slide 12. Base 11 and slide 12 each can be formed of any suitable semi-rigid or rigid nonmetallic or metallic material, such as plastic or aluminum, respectively.

Slide 12 generally is flat, rectangular-shaped, and elongated, and includes straight top and bottom edges 46 and 47, respectively, and straight elongated side edges 48, 49. A longitudinally extending elongated slot 13 is formed in and passes completely through slide 12. A first measurement scale 14, preferably in inches, is located along elongated side edge 48 of slide 12 and extends from top edge 46 of the slide to the intermediate portion of the slide. A second measurement scale 15, preferably in centimeters, similarly is located along opposite elongated side edge 49 of slide 12 and is diametrically opposed to scale 14.

Base 11 generally is flat and trapezoidal-shaped and includes an elongated straight top edge 17 and a short bottom edge 18. First and second openings 19 and 20 are formed in and pass completely through base 11. Slide 12 is slidably captured on base 11 by any suitable fastener, such as a bolt 22, which passes completely through slide slot 13 and base opening 19. A thumbscrew 23 passes completely through a coil spring 24, a washer 25, slide slot 13, base opening 20, and is threadably engaged with a nut 26 for selective adjustment of slide 12 relative to an indicator 27 located on base 11. The operation of improved tractor-trailer ride-height measurement device 10 of the present invention, as best shown in FIGS. 3 and 4, is set forth hereinbelow. However, so that reference can readily be made to one environment in which measurement device 10 operates, a brief description of a tractor-trailer slider, of the type which is well-known to the art and to the literature, is set forth immediately below and is shown at 30 in FIGS. 3 and 4. Slider 30 includes a pair of elongated, spaced apart, parallel main members 31 (only one shown) and a plurality of spaced-apart, parallel cross members (not shown) which extend perpendicularly between and interconnect main members 31. Each main member 31 and cross member generally is a C-shaped beam made of a metal such as steel or other suitable material, but can be other shapes such as an I-shaped beam. A plurality of hangers 32 (only one shown) are mounted on and depend from main members 31 for supporting one or more axle/suspension systems 33. Each axle/suspension system 33 includes generally identical suspension assemblies 34 suspended from each hanger 32. Each suspension assembly 34 includes a suspension beam 35 which is pivotally mounted on hanger 32 in a usual manner. An air spring 36 is suitably mounted on and extends between the upper surface of the suspension beam 35 and main member 31. A shock absorber 37 extends between and is mounted on suspension beam 35 and a certain one of the slider cross members. Other components of suspension assembly 34, mentioned herein only for the sake of relative completeness and to further define one environment in which ride-height measurement device 10 is utilized, include an air brake 38 and a height control valve 39. A cylindrical-shaped axle 40 extends between and is captured in a pair of suspension beams 35 of axle/suspension system 33. Wheels 41 are mounted on each end of axle 40. Slider 30 is movably mounted on a pair of spaced-apart, elongated, parallel rails 42 which are mounted on and depend from the bottom surface of a trailer 43 of a tractor-trailer.

When it is desired to measure an unknown ride-height of slider 30, otherwise described as the vertical distance between an axis or a center point 44 of axle 40 and a bottom surface 45 of a selected one of main members 31 or the cross members of the slider, the following steps are followed as is illustrated in FIG. 3. Elongated top edge 17 of base 11 is placed against bottom surface 45 of slider 30, such as against one of main members 31 or one of the cross members. It can be appreciated that elongated top edge 17 provides at least two reference points on bottom surface 45 of slider 30 so that imperfections, unevenness, or the like on the bottom surface of the selected one of main members 31 or the cross members will not adversely affect the measurement reading obtained from device 10. ^"More specifically, since base top edge 17 is parallel to bottom edge 47 of slide 12 and perpendicular to the direction of movement of the slide when a measurement is taken, it is important that top edge 17 be flush or square against at least two points of contact on bottom surface 45 to ensure an accurate reading. Thumbscrew 23 then is loosened to enable slide 12 to be moved in an upward, or as shown in dot-dash lines in FIG. 3, a downward direction relative to base 11, so that slide bottom edge

47 contacts the uppermost surface of axle 40. Thumbscrew 23 then can be tightened if desired to preserve the measurement, and the distance between axis or center point 44 of axle 40 and bottom surface 45 of slider 30 is automatically indicated by indicator 27 of measurement device 10. It can be appreciated that measurement device 10 automatically compensates for the 2.5 inch radial distance between center point 44 of axle 40 and the uppermost surface of the axle. Thus, the reading shown on device scale 14 by indicator 27 actually is 2.5 inches greater than the distance between base top edge 17 and slide bottom edge 47. This compensation is possible because virtually all axles on North American tractor-trailers are round and five (5) inches in diameter. The indicated measurement then can be compared against the ride-height recommended by the manufacturer of the particular tractor-trailer being measured, and if necessary adjustments can be made to the ride-height using one or more height control valves 39 of axle/suspension system 33. It can further be appreciated that slider 30 is relatively open with only spaced-apart main members 31 and the cross members forming its structure. Thus, if the ride-height is less than the length of slide 12, and since the length of slide 12 is greater than the distance between top and bottom edges 17 and 18, respectively, of base 11, the slide can be moved upwardly into an open space between main members 31 and the cross members to obtain the measurement. As best shown in FIG. 4, when it is simply desired' to ascertain whether the manufacturer recommended ride-height is correctly set on a tractor- trailer, device 10 can be preset to the desired ride-height, and inserted between axle 40 and bottom surface 45 of slider 30. If measurement device 10 will not fit between axle 40 and bottom surface 45, then it is known that the ride-height is too short. Alternatively, if a gap exists between slide bottom edge 47 and the uppermost surface of axle 40, then it is known that the ride-height is too large. In both the former and latter cases, one or more height control valves 39 of axle/suspension system 33 can be adjusted to properly set the ride-height. On the other hand, if measurement device 10 fits between bottom surface 45 and the uppermost surface of axle 40, and base top edge 17 and slide bottom edge 47 each is generally flush against those surfaces, respectively, as illustrated by the dot-dash axle shown in FIG. 4, then it is known that the ride-height is correct.

It is understood that the straight bottom edge 47 of slide 12, rather than a curved bottom edge which would conform to the circumference of axle 40, enables ride-height device 10 to measure in any vertical plane, so long as the device is rotated to a vertical plane unobstructed by components of suspension assembly 34.

It is further understood that thumb screw 23, coil spring 24, washer 25, and nut 26 can be removed and slide 12 can be rotated about bolt 22 to switch from English scale 14 to metric scale 15, or vice versa depending on whether a measurement in inches or centimeters is desired. After slide 12 is rotated about bolt 22, thumb screw 23, coil spring 24, washer 25, and nut 26 can be reassembled. It is also understood that additional markings (not shown) can be placed on base 11 above and below indicator 27, if desired, to indicate a tolerance for deviation from a tractor- trailer manufacturer's recommended ride-height.

It is appreciated that ride-height measurement device 10 can be manufactured in different sizes to accommodate the varying recommended ride- heights for different types of tractor-trailers and even different types of vehicles. It is further appreciated that a top mount type axle/suspension system is shown in FIGS. 3 and 4, but ride-height measurement device 10, by varying its size, can also be utilized for underslung-type axle/suspension systems which are well known to the art and to the literature. It is still further appreciated that measurement device 10 can be changed so that it can be utilized for round or square axles, and axles of sizes other than five (5) inches diameter.

It is understood that measurement device 10 can be utilized on production lines, by fleet mechanics, or in aftermarket maintenance/repair shops. It can also be utilized by a driver on the road to ensure that proper ride-height is being maintained. Moreover, it is understood that measurement device 10 can be used to measure the ride-height between axle center points and the bottom surface of sliders, trailer bodies, or tractor frames.

Also, it is understood that measurement device 10 can even be utilized to measure a distance between two objects, wherein one object provides a stable surface for square placement of base top edge 17, and wherein the second object surface is difficult to measure, such as center point 44 of axle 40.

Thus, it can be seen that the tractor-trailer ride-height measurement device and method of the present invention provides a solution to inaccurate measurement devices and methods heretofore known in the art by eliminating physical measurement and mathematical calculation errors in measuring tractor- trailer ride-heights. The present invention embodies the solution in a device and method which is easy to use, accurate, durable, and inexpensive.

Accordingly, the improved vehicle ride-height measurement device and method is simplified, provides an effective, safe, inexpensive, and efficient device and method which achieves all of the enumerated objectives, eliminates difficulties encountered with prior vehicle ride-height measurement devices and methods, solves existing problems, and obtains new results in the art.

In the foregoing description, certain terms have been used for brevity, clarity, and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed.

Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. Having now described the features, discoveries and principles of the invention, the manner in which the improved vehicle ride-height measurement device is constructed, arranged, and used, the characteristics of the construction and arrangement, and the advantageous, new, and useful results obtained; the new and useful structures, devices, elements, arrangements, parts, and combinations are set forth in the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A device for determining a distance between at least one point on a first object and at least one point on a second object, wherein said second object point is located a certain distance from a point intermediate said first and second object points, said intermediate point being located on said second object, said device including: a) a base, said base having a first surface for contacting said first object point; and b) a slide movably mounted on said base, said slide having a second surface for contacting said intermediate point, wherein said device automatically compensates for the distance between said second object point and said intermediate point.

2. The improved device of Claim 1, in which said base includes an indicator; and in which said slide includes at least one measurement scale, whereby said indicator indicates a measurement on said scale of said distance between said first object point and said second object point.

3. The improved device of Claim 2, in which said indicator is an arrow located on said base adjacent said measurement scale; and in which the measurement scale is in units selected from the group consisting of metric units and English units.

4. The improved device of Claim 3, in which said metric units is centimeters and said English units is inches.

5. The improved device of Claim 1, in which said base first surface is elongated and straight.

6. The improved device of Claim 5, in which said slide is slidably mounted on said base; in which said slide second surface is straight and parallel to said base first surface; and in which the direction of slidable movement of the slide relative to the base is perpendicular to the slide second surface and the base first surface.

7. The improved device of Claim 6, in which said slide is flat, elongated and rectangular-shaped; in which an inches scale is disposed along a first elongated edge of said slide and extends from a first end of said slide to an intermediate portion of said slide; in which a centimeters scale is located along a second elongated edge of said slide and is generally diametrically opposed to said inches scale; and in which said slide is rotatable relative to said base for disposing a selected one of said inches scale or said centimeters scale adjacent to said arrow indicator.

8. The improved device of Claim 7, in which an elongated slot is formed in and passes through said slide; in which a bolt passes through said slide slot and an aligned first opening formed in and passing through said base to rotatably capture said slide on said base; and in which a thumbscrew assembly passes through the slide slot and an aligned second opening formed in and passing through the base for selective slidable movement of said slide relative to the base.

9. The improved device of Claim 8, in which said base is flat and generally trapezoidal-shaped; and in which the base includes a straight edge spaced from, parallel to and shorter than said base first surface.

10. The improved device of Claim 9, in which said base and said slide each is formed of a material selected from the group consisting of semi-rigid and rigid materials.

11. A method of measuring the distance between at least one point on a first object and at least one point on a second object, wherein said second object point is located a certain distance from a point intermediate said first and second object points, said intermediate point being located on said second object, a device for measuring said distance including a base, said base having a first surface for contacting said first object point, and a slide slidably mounted on the base, said slide having a second surface for contacting said intermediate point, wherein said device automatically compensates for the distance between said second object point and said intermediate point, the slide having at least one measurement scale located thereon adjacent to an indicator located on the base, said slide being movable relative to said base and in a direction perpendicular to the slide second surface and the base first surface, said method including the steps of: a) contacting said base first surface against said first object point; b) sliding said slide second surface relative to said base and contacting said slide second surface against said intermediate point; and c) reading said distance measurement by the position of said base indicator relative to said slide measurement scale.

12. A method of measuring a predetermined distance between at least one point on a first object and at least one point on a second object, wherein said second object point is located a certain distance from a point intermediate said first and second object points, said intermediate point being located on said second object, a device for measuring said distance including a base, said base having a first surface for contacting said first object point, and a slide slidably mounted on the base, said slide having a second surface for contacting said intermediate point, wherein said device automatically compensates for the distance between said second object point and said intermediate point, the slide having at least one measurement scale located thereon adjacent to an indicator located on the base, said slide being movable relative to said base and in a direction perpendicular to the slide second surface and the base first surface, said method including the steps of: a) adjusting said slide relative to said base, said predetermined distance measurement on said slide scale being slidably moved with the slide adjacent to said base indicator; b) sliding said slide second surface relative to said base and contacting said slide second surface against said intermediate point; and c) determining by visual inspection whether said distance between said first object point and said intermediate point is greater than, equal to, or less than said predetermined distance by the position of said slide second surface relative to said intermediate point.