US2867432A - Load indicating means - Google Patents

Description

Jan. 6, 1959 s. BARKER ETAL 2,867,432

LOAD INDICATING MEANS Filed Dec. 1'7, 1953 4 Sheets-Sheet l Page/v41. J14- H-m/M/LLE STEPHEN BaezE/e,

IN V EN TORS.

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Jan. 6, 1959 s. BARKER ET AL LOAD INDICATING MEANS 4 Sheets-Sheet 2 Filed Dec. 17, 1953 J EZCII AL M HEM/MILL 5e, STEPHEN .baezsxg.

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IN V EN TORSI drive/ways.

Unite States Patet LOAD INDICATING MEANS Stephen Barker, Alhambra, and Percival M. Heinmiller,

La Canada, Califi, assignors to Utility Trailer Mannfacturing Company, Los Angeles, Calif., a corporation of California Application December 17, 1953, Serial No. 398,677

1 Claim. (Cl. 265-40) This invention has to do generally with load indicating means, and is more particularly concerned with indicating means adapted particularly well to the measuring of relatively heavy loads, though not limited thereto.

While there are many different environments in which the device may be used to advantage, it is particularly well suited to the weighing of vehicle loads, and, even more particularly, to the weighing of loads on logging vehicles which individually are usually made up of a truck connected by a draft and steering reach to a dolly or trailer, the logs spanning the space between truck and trailer and end-resting on bunks carried by those units.

Therefore, without limiting our invention thereto, we will limit the description to this particular embodiment. We also wish to state at the outset that While our invention contemplates a device that may be calibrated to any suitable unit of weight, for the sake of simplicity we will confine the description to its use in a situation, as in most log hauling operations, where it is only necessary to know that the load does not exceed a legal weight limit and yet is close enough to that limit to assure that there is no undue waste space on the vehicle.

It is well recognized that the service conditions under which log-hauling vehicles operate are most severe. Not only are the loads exceedingly heavy and the road conditions of the worst, but the shocks of loading, draft and unloading are of extremely high order. It is therefore a general object of the invention to provide a device which is sufliciently rugged to stand up well under all these exceptional conditions of operation and yet is amply sensitive to give accuracy of a degree well within the required limits. And yet the device is such that its parts may be relatively light and uncumbersome, to obvious advantage.

In the first place, the device is applied in such a manner that only a portion of the load is directed upon it and that portion is distributed among several units. As a particular feature, the indicator operating device is exposed only to vertical compression loads imposed by the lading, and it is independent of the forces of draft, torque and traction incident to operation of the vehicle. Accordingly, it is not exposed to such forces, thus greatly reducing the necessity for providing the massiveness and structural strength necessary to devices that are not thus independent. At the same time, the device is such that it may remain in operation at all times. That is, it remains operative during loading, travel and unloading in spite of the special stresses and strains imposed upon it as incidents to such operations. The arrangement is such that these stresses and strains, where unavoidably imposed on the device, are reduced to a minimum, and at the points of such imposition the device is fashioned to be fully and effectively resistant.

The device is easily and readily installed and serviced, matters which are of decided importance in apparatus of this type, as is well understood by those working in the art.

In its preferred form the device operates in a closed Patented Jan. 6, 1959 hydraulic system. It is therefore susceptible to temperature changes, but the arrangement is such that the volume of fiuid is remarkably small and hence the effect of temperature change is reduced to a minimum. However, such variations as do occur by reason of temperature changes are fully taken into account and compensated for, as will appear from the detailed description which follows.

Other objects and features of novelty will appear in the following detailed description, reference being had to the accompanying drawings, in which Fig. 1 is a side elevation of a log-hauling vehicle equipped with our invention,

Fig. 2 is an enlarged, rear elevation of the trailer,

Fig. 3 is a section on line 33 of Fig. 2,

Fig. 4 is an enlarged, horizontally contracted detail section on line 4-4 of Fig. 1,

Fig. 5 is a side elevation of Fig. 4,

Fig. 6 is an enlarged detail section on line 6-6 of Fig. 2, the bowing of certain members being represented in greatly exaggerated form,

Fig. 7 is a bottom plan view of one of the plates of the assembly,

Fig. 8 is a top plan view of another of the plates of the assembly,

Fig. 9 is a side elevation of Fig. 8,

Fig. 10 is a bottom plan view of a hydraulic capsule,

Fig. 11 is a section on line 11- 11 of Fig. 10,

Fig. 12 is a face view of a conventional gage that may be used in connection with the apparatus,

Fig. 13 is a view generally similar to Fig. 6, but showing a different type of capsule and capsule-mount,

Fig. 14 is an enlarged, detail section of a fragment of the capsule of Fig. 13,

Fig. 15 is a medial section through a variational 'type of capsule,

Fig. 16 is a schematic view showing a variational type of indicator operating mechanism; and Fig. 17 is a schematic view showing another type of lndicator mechanism and a variational arrangement of structural plates.

In Fig. 1 we have indicated schematically at 10 a log-hauling vehicle made up of truck 11 connected in the usual manner by a steering reach 12 to the dolly or trailer 13. The trailer has a usual under-structure 14 made up of a central box member 15 (Figs. 2, 3 and 6) with which the reach tube 16 is integrated and which is spring-supported at 17 from wheels 18 in the usual manner. An upper structure 19, in the form of a sub-bunk 20 and a bunk 21 connected in the usual manner by a turntable and king-pin assembly 22, overlies under-structure 14 and is connected thereto in a manner to be described. It is upon bunk 21 that the rearward ends of logs L are loaded.

The truck 11 (Figs. 4 and 5) includes an under-structure 14a which, in turn, includes a frame 23 to the longitudinal members 23a of which are fastened at 24 the stringers 25 and inverted channels 26. Frame 23 is springsupported at 1711 in the usual manner, not here disclosed in detail since it makes up no part of the present invention. An upper truck structure is indicated at 19a and includes a sub-bunk 29a and a bunk 21a which are connected in the usual manner by a turn-table and king-pin assembly 22a. Structure 1% is connected to structure 14a in a manner to be described. Rigidly connected to frame 23 i a hook to take the forward end of reach 12. It is upon bunk 21a that the forward ends of logs L are loaded. The logs are chained together in the usual manner, it being understood that the logs themselves form the draft connection between truck and trailer, as is usual.

Since the four connections C between the under and upper structures of the truck and trailer are alike, only one need be described in detail, and for this purpose we have chosen the connection between the structures of the trailer. Similarly, just as there are two weight indicator operating devices A and B on trailer 13, one at each side of and equally spaced from king-pin 22, there are two identical weight indicator operating means A and B on truck 11, one at each side of and equally spaced from king-pin 22a. The means A and B and king-pin 22 are in transverse alinement, as are also means A, B and king-pin 22a. There is a weight indicating means supported at each connection C.

The connections C between the upper and lower structures of the truck and of the trailer each include upper and lower plates. In each case the lower plate is welded to a member of the under structure: in the case of the trailer the welding is to the box 15, while in the case of the truck the welding is to channel 26. Otherwise the connections are alike and a description of a trailer connection will suflice for an understanding of the truck connections.

Referring particularly to Figs. 2 to 9, it will be seen that each connection C embodies a lower horizontal plate 27 and a parallel upper plate 28 spaced vertically thereabove. The plates are of generally rectangular shape, there dimension of greater length extending longitudinally of the trailer. The lower plate 27 is welded to the top of box 15, while the upper plate is welded to the under side of sub-bunk 2t Welded to the center of the upper face of lower plate 27 is a circular pressure plate 29, while circular pressure plate 30 is welded to the center of the lower face of upper plate 28, the two pressure plates being thus axially alined. As will appear, the weight indicator operating means A is taken between and centered with pressure plates 29 and 30. It will be seen that the ends 31 of plates 27 and 28 extend horizontally outwardly beyond their points of connection with the under and upper structures 14 and 19, respectively, so, under certain circumstances they may flex to limited extents. The spacing between plates 27 and 28 is maintained by cross-lugs 32 welded to the free ends 31 of one of the plates, here, the lower plate 27. Bolts 33 extend through lugs 32 and upper plate 23, through bolt-carried, spacing washers 34 of pre-selected thickness and number may be inserted between lugs 32 and plate 28 for a purpose to be set forth later.

It will be seen that the forces of draft, torsion and traction between structures 14 and 19 are transmitted through plates 27, 28 and bolts 33, and it will later appear that mechanisms A, A, B and B are so associated with the structures that none of these forces are transmitted through those mechanisms. Plates 2'7, 28 are sufficiently sturdy and rigid that they effectively transmit such forces without harmful distortion, but are sutficiently resilient that they may be flexed to the limited extent explained below, which is, of course, well within the elastic limit of the stock. As an example, though this is not at all limitative, it has been found that mild steel plates of /2 thickness serves the purpose well. Likewise, lugs 32 may be 1" thick mild steel and bolts 33 may be of about 1" diameter. Circular pressure plates 29 and 30 may be fashioned from mild steel sheets about thick, and, in the example shown, are about 7" in diameter.

The weight indicator operating means A is in the nature of a metal hydraulic capsule 35 (see particularly Figs. 6, l and 11) which is capable of limited inflation under the imposition of internal fluid pressure; that is, its upper and lower walls are capable of relative vertical displacement under differential internal pressure conditions. In its preferred form, capsule 35, of mild steel, is made up of upper and lower circular disks 36 and 37, respectively. Disk 37 is shaped as a shallow cup, the main body portion or wall 38 being relatively thin and the rim portion 39 being relatively thick. The upper face 40 of rim 39 ismachined flat, while the inner peripheral face 41 of the rim is turned smooth and is squarecut, except for the slight bottom radius 42.

Upper disk 36 has a relatively thick body portion or wall 43 and a relatively thin, annular flange portion 44. Body portion 43 is of a diameter to have interference fit within rim 39, the peripheral face 45 being finished and square cut. The under face 46 of flange 44 is finished flat, and the flange is of somewhat greater outside diameter than is rim 39. When the two disks are pressed together to engage faces 41 and 45 on the one hand, and faces 44), 46 on the other hand, there is left between the under face 47 of disk 36 and the upper face 48 of disk 37 a vertical spacing 49 of about This space 49, as peripherally defined by face 41, forms the internal pressure chamber D of the capsule. Preferably the lower corner of body portion 43 is chamfered at 50.

As a preferred method of hermetically sealing the capsule at the joint between disks, and at the same time forming a bond which effectively resists the relatively severe disruptive forces, We prefer to proceed as follows. After the disks have been tightly pressed together, they are skip-welded as at 51, the extension of flange 44 beyond rim 39 providing a convenient area for the welds. The assembly is then placed in a furnace and copper brazed. The brazing material M creeps in between faces 46', 45 and 41, 45 by capillary attraction and finally provides a very strong peripheral bond between the two disks. Preferably, before the disks are assembled, all opposed faces of the disks, except those named just above, are painted with chromic acid or the like to form a stop which prevents the brazing together of the painted faces and thus preserves full volumetric capacity Within the capsule. During operation of the device, as will be described, the described step joint between disks effectively resists the disruptive forces. The vertical step MV, of the brazed joint between faces 41 and 45 is in ations in load, which variations cause a variation in the- In turn, the variations in pres-- flexing of disks 36, 37.

sure actuate certain indicating means. The proportions of the disks and disk parts are particularly well adapted For instance, the parts of the disksto the purpose. which do the most flexing are relatively thin and flexible,

whereas the outer, annular portion of the capsule, where the parting stresses are concentrated, are relatively stiff and thick. Both disks are free to flex, and thus the sensitivity of the capsule is increased. By varying the thickness of the body portions of the disk walls, the sensitivity of the capsule may be altered at will. Further, the circular shape contributes to the ease and evenness of flexure and hence to the sensitivity. Still further, the cir cular shape allows chamber 49 to be relatively small, so the volume of trapped fluid is relatively small and hence there is relatively little volumetric change due to chang-. ing temperature conditions.

As illustrative, but not limitative, dimensions which serve the purpose well, chamber 49 is about 10" in diameter, step 41 is about wide, step 45 is about wide, annular face 40 is about 1" wide, face 46 is about 1%" wide, wall 39 is about thick, and wall 43,

including the portion fitted into the cup of the lower plate,

is about /2" thick.

Opening through the center of lower disk 37 and extending to chamber 49, is a pressure passageway 53 to take fitting 54 of a pressure line 55. Opening through disk 36 is a passageway 56 which serves as a bleed port during the filling of chamber 49, and is thereafter closed by plug 57. Depending fro-m disk 37 are the diametrically opposite, locating lugs 58, which, when the capsule is placed between plates 27 and 28 fit loosely in notches 59 in the edges of plate 27. The lug and notch registration holds the capsule 35 centered and against other than limited horizontal displacement with respect to plates 27 and 28. Except for the vertical confinement of the capsule by said plates, lugs 58 provide the only connection between plates and capsule, and thus the forces of draft, torque, traction, loading and unloading are transmitted from plate to plate without being imposed on the capsule, all to obvious advantage. The capsule may be considered as floating between the plates, at least to a limited extent.

Upper plate 28 is notched at 66 to give access to bleed port 56, and lower plate 27 and pressure plate 29 are centrally apertured at 60a to take pressure line 55. Line 55 joins a similar pressure line 61 leading to the capsule of unit B, both lines being connected by line 62 which extends to a charging and pressurizing valve, conventionally shown at 63, and pressure gage 64 (Fig. 12). While this gage may be of an suitable type, it preferably has a pressure-actuated hand 65, and a pair of pointers 66 and 67. The pointers are of a usual type, being frictionally held in adjusted positions of included angularity, and being bodily rotatable as a unit by means of a thumb nut 68.

With bolts 33 loosened, the bunk and sub-bunk assembly is raised and capsule 35 is slipped between plates 27 and 28, with lugs 58 entered in notches 59, and pressure line 55 is connected to the capsule. The bunk and subbunk assembly is then lowered until pressure plate 30 centrally engages the upper disk 36 of the capsule. Spacer or cross-lugs 32 are of such diminished height with respect to the thickness of the capsule that, in the situation just described, plate 28 is spaced vertically above said lugs. Consequently, when bolts 33 are fully tightened to bring plate 28 down upon lugs 32, the plates 27 and 28, or at least their free ends 31, are slightly flexed or bowed, as shown in exaggerated manner in Fig. 6. The amount of such pre-stressing of the plates, which has eflect on the sensitivity of the device, may be varied by inserting washers 34, of preselected number and/or thickness, between lugs 32 and plate 28.

With the capsule 35 installed between plates 27 and 28, or, more precisely, between pressure plates 29 and 30, and the pressure lines connected up as has been described, bleed port 56 is opened and the lines and chamber 49 are charged with a suitable liquid, for instance, a very light oil such as #9 ice-machine oil, which contains a very low content of entrained air. The bleed port is then plugged and pressure within chamber 49 is built up to about 140 pounds per square inch. This has the effect of slightly inflating the capsule, which forces an accompanying additional slight bowing of plate-ends 31. The actual extent of inflation is very slight, say about .030 to .040" at the center of chamber 49, but it is ample for the purpose. There is, of course, slight stretching of the metal of the capsule during the inflation.

It will be seen that, with the capsule in this condition, an additional load placed on the upper structure 19 will impose vertical, down bearing, compressive force on capsule 35, and this force, in tending to flatten the capsule, will increase the pressure of the liquid within chamber 49, the increase being indicated on gage 64 by the swing of hand 65.

Of course, gage 64 may be calibrated in units of weight so a direct reading of the weight may be made from the gage, but such calibration is not necessary to the loading and hauling operations which we are describing. In such operations, it is merely necessary to insure, on the one hand, that the load is not above the legal limit and, on the other hand, to be sure that the pay load is not too light for economical operation.

While the exact procedure need not be described, the following discussion will outline what, in essence, the operator may do in order to ascertain the load condition. When the operator first secures his equipped vehicle, he notes the pressure indicated by needle 65 on gage 64 when the vehicle is unloaded. Say the indicated pressure is The operator then loads the vehicle with what, in his judgment, is normal or just within the legal limit. He then weighs the entire loaded vehicle and notes the change in pressure on gage 64. Say that the gage now reads 180# and that the weight of the loaded vehicle is just within the legal limit. He then knows that a differential of 40# between unloaded and loaded condition represents the allowable pay load. If there were no temperature-change conditions to be taken into account, the operator would then, in all his subsequent loadings, know that he was properly within the legal limit whenever the gage read 1804i. However, temperature changes have to be taken into account, for the vehicles operate under radically different temperature conditions. And a change in temperature will change the pressure within chamber 49 and this will be reflected in a change in the reading of gage 64. For instance, on a hot day the pressure will rise and the needle 65 may register when the vehicle is empty. To reach the pressure will then have to rise only 30# and this does not represent a pay load which is anywhere near the allowable limit.

This situation is taken care of in the following manner. As was said, on the first weighing and pressure comparison, it developed that the 4041- differential represented the pay load. The operator therefore spreads pointers 67 and 66 to an included angle that represents 40# on the scale of the gage. Thereafter, whenever preparing to load (and before loading starts), the operator places pointer 66 directly over needle 65. Pointer 67 will then indicate the pay load limit, and the loading will proceed until needle 65 registers with or is satisfactorily close to pointer 67.

It lies within the broader scope of our invention to utilize different types of capsules or indicator operating means and yet secure the beneficial results flowing from that part of the invention which has to do with by-passing the forces of draft, torque, etc. around the operating mechanism. One such variation is illustrated in Figs. 13 and 14. Here, there is no mechanical pre-stressing of lower and upper plates 27a and 28a, respectively, though such plates are connected to one another by spacers and bolts 32a and 3301, respectively, and to upper structure 1% and understructure 14a, in manners generally similar to those previously described. Here, however, capsule 35a is in the nature of an inflatable rubber bag, being made up of a circular disk of oil resistant rubber which has a central parting 70 forming upper and lower walls 71 and 72, respectively, which walls terminate in the integral, solid, annular peripheral or rim portion 74. Preferably, reinforcing wires 75 and 76 are molded into portion 74, the wires 76, which are of relatively small diameter, being positioned at the outer edge of parting 70 and serving to resist the tendency of the rim to split at this point when the capsule is inflated. A central metal fitting 75 is molded into wall 72 and is centrally apertured to take nipple 76' whereby connection is made to pressure line 55a.

Capsule 35a is held against horizontal displacement with respect to plates 27a and 28a by a ring-flange 77 upstanding from and welded to plate 27a. This flange extends upwardly beyond the top of capsule 35. A cir-.

cular pressure plate 78, welded to plate 28a, engages the upper face of capsule 35, and has loose fit within ring 77. Said ring acts not only as a locator for capsule 35 but also prevents extrusion of the rubber of the capsule when the latter is exposed to vertical compressive forces.

It will be seen that the capsule 35a may be pre-charged and inflated with a pressure-fluid, such as oil, in the manner described above, such inflation bowing the free ends of plates 27a, 28a. Thereafter, the loading of the upper structure will raise the pressure within the capsule and cause a corresponding response on an indicating instrument similar to gage 64.

In Fig. we have shown a capsule which may be used in connection with the supporting and confining structure of Fig. 13. Here, the capsule b is made up of two circular, metal diaphragms and 81, to the peripheries of which is bonded a rubber ring 82, said ring hermetically sealing the space between diaphragms but permitting said diaphragms to spread apart or bow vertically when exposed to internal inflating pressure, the pressure fluid being admitted through fitting 83 which is part of a charging and gage line similar to those previously described. Preferably, a metal channel-ring 84 is clamped around the rubber ring 82, to limit the separative movement of walls 80, 81 and to insure a good seal between the diaphragm peripheries.

It will also be apparent that the invention contemplates in its broader aspects, an arrangement such as is schematically shown in Fig. 16 wherein the plate structure is generally similar to that previously described but wherein a rubber capsule 85, serving merely as a liquid reservoir, is interposed between plates 27:; and 28b. The liquid in this capsule is not pressurized but is merely led through line 55b to the small-bore, vertical standpipe 87 which terminates, at a level well above the capsule, in a sight glass gage 88. Here, the liquid in capsule is merely displaced when plate 28b deflects under a load imposed on upper structure 19, the extent of displacement as indicated by the rise of the liquid level in gage 88 giving a measure of the extent of deflection and hence of the relative load.

In Fig. 17 there is schematically shown an arrangement wherein plates 27c and 28c are spaced apart by heavy springs 90 which surround bolts 33c; plate 280 being thus resiliently supported on plate 270. Positioned centrally between the plates is a dial indicator 91 adapted to measure deflection, the case of the indicator being secured to plate 27c at 92, and the spring-pressed, handoperating plunger 93 being in constant pressural engagement with plate 28c. As in the other cases, all forces of torque, transmission, etc. are transmitted through the plates and bolts, and not through the indicator or its 3 operating mechanism. On the other hand, vertical forces of compression, as applied by the load to upper structure 19c, will cause a bodily depression of plate 280 against the action of springs 90, and thus actuate the dial indicator.

While we have shown and described preferred embodiments of our invention, various changes in design, structure and arrangement may be made without departing from the spirit and scope of the invention.

We claim:

in combination, a vehicle under-structure which is spring-supported from the vehicle wheels, a lading-taking structure on top of the under-structure, means connecting the two structures and acting to transmit, from one to the other, forces of torque, draft and traction, said means including a pair of elongated vertically opposed horizontally extending members, vertical spacers between the members near their free ends, bolts extending through the spacers and connecting said members, a hydraulic capsule between the members and between said spacers, the spacers being of less vertical extent than is the capsule, whereby, when said bolts are taken home, the upper member is bowed out of a horizontal plane.

References Iited in the file of this patent UNITED STATES PATENTS 388,874 Howard Sept. 4, 1888 1,007,451 Kitts Oct. 31, 1911 1,819,987 Hodge Aug. 18, 1931 2,020,307 Fitch Nov. 12, 1935 2,452,124 Huston et al Oct. 26, 1948 2,646,272 Swift July 21, 1953 2,663,562 Hendrickson Dec. 22, 1953 2,666,634 Williams Jan. 19, 1954 2,680,013 Flath June 1, 1954 2,704,661 Maugh Mar. 22, 1955 FOREIGN PATENTS 195,793 Great Britain Apr. 12, 1923

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