CA1063627A - Tandem suspension assembly bushing - Google Patents
Tandem suspension assembly bushingInfo
- Publication number
- CA1063627A CA1063627A CA273,136A CA273136A CA1063627A CA 1063627 A CA1063627 A CA 1063627A CA 273136 A CA273136 A CA 273136A CA 1063627 A CA1063627 A CA 1063627A
- Authority
- CA
- Canada
- Prior art keywords
- insert
- sleeves
- suspension assembly
- tandem suspension
- assembly according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60G—VEHICLE SUSPENSION ARRANGEMENTS
- B60G5/00—Resilient suspensions for a set of tandem wheels or axles having interrelated movements
- B60G5/02—Resilient suspensions for a set of tandem wheels or axles having interrelated movements mounted on a single pivoted arm, e.g. the arm being rigid
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Springs (AREA)
- Vehicle Body Suspensions (AREA)
- Vibration Prevention Devices (AREA)
Abstract
Abstract of the Disclosure A tandem suspension assembly bushing for heavy duty trucks which includes a pair of parallel equalizing beams, a resilient support at each end of the beams, and end brackets connecting each support to a pair of spaced, parallel cross axles. A beam center bushing is located at the midportion of each equalizing beam to connect a spring saddle or frame bracket to each equalizing beam. Each beam center bushing comprises inner and outer sleeves and a tubular, cylindrical, elastomeric insert is positioned between the sleeves. To prevent relative movement between the insert surfaces and the sleeves, particular-ly in situations where there exists conical twisting between the inner and outer sleeves, the insert is adhesively attached to the sleeves and the elastomeric insert is placed in a state of compression by deforming the outer and/or inner sleeve to radi-ally compress the wall of the insert. Alternatively, the insert is post bonded to the inner and outer sleeve without radial deformation of the sleeves.
Description
63t;;~7 This invention relates to a tandem suspension arrangement for heavy duty trucks. Tandem suspension units have been employed for many years on heavy duty on- or of~-the-road trucks. The suspension employs equalizin~ means which utilize the "lever"principle to distribute the load between the axles and to reduce the effect of bumps and road irregularities. ' Torque rods assist in the absorption of torque, which is the tendency of the axles to turn backwards or forwards on their neutral axes~ due to drive or braking forces. Resilient sup-ports, such as rubber bushings, are employed at the ends of mostequalizing beams to connect those beams to the axle brackets and a center bushing is located at the midportion of each equalizing beam to connect a spring saddle or frame bracket to each ~eam.
The bushings eliminate the necessity for lubrication fittlngs at those locations.
~' Center bushings which mount the equalizing beams for movement relative to a spring saddie or frame bracket comprise i~ an inner sleeve and an outer sleeve. An elastomeric insert is provided between those sleeves and is intended to cushion the loading between the equalizing beam and frame bracket as the '` ' tandem wheels are subJected to road irregularitLes. Thus, at ~ ' times, the elastomeric insert is sub~ected to torsional loads as one of the wheels encounters a bump or hole in the road to ;,`! .:
~, attain a different elevation as compared to the other wheels.
The insert is at times sub~ected to shear forces when the '1~ sleeves ~ove axially and in opposite directions, for example, '~ ;; when the vehicle turns a'corner. Furthermore, under some driv- ' ' ` ing conditions, such as the veh~cle turning a corner, the center '' ~ beam bushing is æub~ected to conical deflection wherein the ;~ 30 axe5 of the inner and outer sleeves become misaligned and tend ,' ' " , , ' , ~ ` "~
., ' ' . .
, , 1~636;~7 .
to trace a conical path. In these motions~ it is - important that slippaEe between the metal sleeves and the insert is minimized to ensure dissipation ; of energy in the insert rather than at the inter-face between the insert and its sleeves. If there exists continued or excessive relative movement between the insert and the sleeves~ abrasion, wear, and, eventually, failure of the part will occur.
- An attempt to improve the ~atigue life of the beam center bushing is set forth in U.S.
. . .
Patent No. 3~666,335, granted to Arthur Mundy.
In that patent, there is disclosed a beam center `~` bushing comprising a pair of concentric, spaced-~ apart, rigid sleeves, one inside the other, and ., an elastomeric insert radially compressed and .~....................................................................... . ..
^i occupying between about 70 to 90 percent of the space therebetween. Abrasion-resistant sleeves are provided at the ends of the insert between the two rigid sleeves in contact with one of those sleeves and normally &paced a distance from the other sleeve. This arrangement has some draw-.,:, backs, in that the elastomeric insert does not occupy Substantially all of the available space ::between the rigid sleeves, khus decreasing the amount of metal-to~insert contact, which increases ~ iJ
¦ ~ the radial stresses on the insert. Furthermore, since the abrasion-resistant sleeve is relatively 9~ hard as compared to the insert, radial or conical ::t cushioning is counteracted, and this de~eats one purpose of the bushing andproduces an impact ef~ect due to the sudden contact between the rigid sleeve .~ .
~ and the semirigid abrasion-resistant bushing.
.. ..
. ~ , ~ . . "~ , ., ~ . :, ,, . , ~ , 1~63627 Truck tandem uspension systems are subjected to conditions which very frequently apply a conical load on the center bushing. When this conical load is repea~edly severe it deflects the bushing so that the elastomeric insert is released from a state of compression at its axial ends, and the insert starts to abrade which causes a progressive reduction in the compression. Repeated abrasion and reduction of compression results in the disintegration of the elastomeric member. In the present invention the elasto-:
meric insert is also placed under compression but isadditionally adhesively bonded so that at all times the ;- rubber surfaces are adherad to the metal surfaces and do not :~ b ecome abraded through lack of compression. This has a marked --influence on the durability of the bushing as the loss of the -~ elastomeric material due to abrasion is avoided.
:
The pre~ent invention overcomes many of the fore- -:: .
going prior art problems by providing a kandem suspension ~-having a beam center bushing which is constructed in such a manner as to minimize the tendency of the bushing insert to r~; 20 move relative to its inner and outer sleeves. This is `~ accomplished while providing maximum in~ert-to-metal contact ~` area.
, ~ . .
~;~ According to the invention there is provided a tandem su3pen~ion assembly for heavy duty trucks and the like, comprising, (a) a pair of parallel equalizing beams; (b) support means at the end of each beam; ~c) end bracket~
., connected to each support mean~ a pair o~ spaced, parallel -; cros~ axles mounted on said end brackets; (d) a center bushing . .
at the midportion of each equalizing beam; and (e) bracket means connected to each equalizing beam by its center bu~h-- ing each ~aid center bu~hing compri~ing an inner cylindrical sleeve, an outer cylindrical ~leeve, and a tubular, cylindrical, :, _ 3 --.,,, ~), , ~L~63~;2~
elastomeric insert positioned between said sleeves and being adhesively bonded thereto, said insert having a first portion occupying substantially all of the available space between said inner and outer sleeves, said insert having a second portion comprising annular axially facing end surfaces, said end surfaces each extending axially beyond said available space and being unconstrained both axially and radially under all loading conditions, and said first portion of said insert being in a state of radial compression.
~` 10 More specifically, the invention includes a tandem axle assembly having a beam center bushing compris-ing an inner sleeve and an outer sleeve. According to one aspect of the present invention, a tubular cylindrical, -- -elastomeric insert is positioned between the sleeves and i9 adhesively bonded thereto. The outer and/or inner sleeve - -.:, . . .
; is swaged to compress the elastomeric insert. According to another aspect of this invention, an insert is . . :
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~ 63~7 provided having a wall thickness greater than the space pro-vided between the inner and outer sleeves. A heat activated ' adheslve is applied to the inner surface of the outer sleeve and to'the outer surface of the inner sleeve. The insert is then forced between the sleeves and the adhesive is actlvated to bond the insert to the sleeves. Desirably, the insert is .
' compressed to a thickness of between about 45 and 55 percent ~
of its unc~mpressed thickness. For many applications, it is ~-desirable that the axial length of the insert as compared to its thickness be a ratio in excess of 12 For a better understanding of the present invention, ' together with other and further ob,~ects thereof, reference is had to the following description taken in connection with the ... .. .
' accompanying drawings, and its scope will be pointed out in the ' appended claims.
,`.1 . .
In the drawings: ~' Figure 1 is a fragmentary, perspective view of one .~. : . .
type of tandem suspension assembly which embodies the present invention; ' '- ' Figure 2 is a cross sectional view of a beam center ... ; .. . .
;'',!, ' bushing according to this invention, showing the bushing in a ~'~ normal, unloaded state; ' '-~`1 . . . . . .
~~ ' Figure 3 is a cross sectional view similar to Figure ~
,,, : ~, . .
'~ 2, but showing the bushing in one mode of conical stress;
Figure 4 is a cross sec'tional view similar to Figure
The bushings eliminate the necessity for lubrication fittlngs at those locations.
~' Center bushings which mount the equalizing beams for movement relative to a spring saddie or frame bracket comprise i~ an inner sleeve and an outer sleeve. An elastomeric insert is provided between those sleeves and is intended to cushion the loading between the equalizing beam and frame bracket as the '` ' tandem wheels are subJected to road irregularitLes. Thus, at ~ ' times, the elastomeric insert is sub~ected to torsional loads as one of the wheels encounters a bump or hole in the road to ;,`! .:
~, attain a different elevation as compared to the other wheels.
The insert is at times sub~ected to shear forces when the '1~ sleeves ~ove axially and in opposite directions, for example, '~ ;; when the vehicle turns a'corner. Furthermore, under some driv- ' ' ` ing conditions, such as the veh~cle turning a corner, the center '' ~ beam bushing is æub~ected to conical deflection wherein the ;~ 30 axe5 of the inner and outer sleeves become misaligned and tend ,' ' " , , ' , ~ ` "~
., ' ' . .
, , 1~636;~7 .
to trace a conical path. In these motions~ it is - important that slippaEe between the metal sleeves and the insert is minimized to ensure dissipation ; of energy in the insert rather than at the inter-face between the insert and its sleeves. If there exists continued or excessive relative movement between the insert and the sleeves~ abrasion, wear, and, eventually, failure of the part will occur.
- An attempt to improve the ~atigue life of the beam center bushing is set forth in U.S.
. . .
Patent No. 3~666,335, granted to Arthur Mundy.
In that patent, there is disclosed a beam center `~` bushing comprising a pair of concentric, spaced-~ apart, rigid sleeves, one inside the other, and ., an elastomeric insert radially compressed and .~....................................................................... . ..
^i occupying between about 70 to 90 percent of the space therebetween. Abrasion-resistant sleeves are provided at the ends of the insert between the two rigid sleeves in contact with one of those sleeves and normally &paced a distance from the other sleeve. This arrangement has some draw-.,:, backs, in that the elastomeric insert does not occupy Substantially all of the available space ::between the rigid sleeves, khus decreasing the amount of metal-to~insert contact, which increases ~ iJ
¦ ~ the radial stresses on the insert. Furthermore, since the abrasion-resistant sleeve is relatively 9~ hard as compared to the insert, radial or conical ::t cushioning is counteracted, and this de~eats one purpose of the bushing andproduces an impact ef~ect due to the sudden contact between the rigid sleeve .~ .
~ and the semirigid abrasion-resistant bushing.
.. ..
. ~ , ~ . . "~ , ., ~ . :, ,, . , ~ , 1~63627 Truck tandem uspension systems are subjected to conditions which very frequently apply a conical load on the center bushing. When this conical load is repea~edly severe it deflects the bushing so that the elastomeric insert is released from a state of compression at its axial ends, and the insert starts to abrade which causes a progressive reduction in the compression. Repeated abrasion and reduction of compression results in the disintegration of the elastomeric member. In the present invention the elasto-:
meric insert is also placed under compression but isadditionally adhesively bonded so that at all times the ;- rubber surfaces are adherad to the metal surfaces and do not :~ b ecome abraded through lack of compression. This has a marked --influence on the durability of the bushing as the loss of the -~ elastomeric material due to abrasion is avoided.
:
The pre~ent invention overcomes many of the fore- -:: .
going prior art problems by providing a kandem suspension ~-having a beam center bushing which is constructed in such a manner as to minimize the tendency of the bushing insert to r~; 20 move relative to its inner and outer sleeves. This is `~ accomplished while providing maximum in~ert-to-metal contact ~` area.
, ~ . .
~;~ According to the invention there is provided a tandem su3pen~ion assembly for heavy duty trucks and the like, comprising, (a) a pair of parallel equalizing beams; (b) support means at the end of each beam; ~c) end bracket~
., connected to each support mean~ a pair o~ spaced, parallel -; cros~ axles mounted on said end brackets; (d) a center bushing . .
at the midportion of each equalizing beam; and (e) bracket means connected to each equalizing beam by its center bu~h-- ing each ~aid center bu~hing compri~ing an inner cylindrical sleeve, an outer cylindrical ~leeve, and a tubular, cylindrical, :, _ 3 --.,,, ~), , ~L~63~;2~
elastomeric insert positioned between said sleeves and being adhesively bonded thereto, said insert having a first portion occupying substantially all of the available space between said inner and outer sleeves, said insert having a second portion comprising annular axially facing end surfaces, said end surfaces each extending axially beyond said available space and being unconstrained both axially and radially under all loading conditions, and said first portion of said insert being in a state of radial compression.
~` 10 More specifically, the invention includes a tandem axle assembly having a beam center bushing compris-ing an inner sleeve and an outer sleeve. According to one aspect of the present invention, a tubular cylindrical, -- -elastomeric insert is positioned between the sleeves and i9 adhesively bonded thereto. The outer and/or inner sleeve - -.:, . . .
; is swaged to compress the elastomeric insert. According to another aspect of this invention, an insert is . . :
~ ~ .
. ~, .
,~ ~
. ,~ .
:.
,.. .
, ,. ~,: .
,. : ' . r ; ' .
':~
~:'~, ' ' ' ~, .
J
- , -- 4 --.i , :.,: . . . ~ :
, . . ..
"``
~ 63~7 provided having a wall thickness greater than the space pro-vided between the inner and outer sleeves. A heat activated ' adheslve is applied to the inner surface of the outer sleeve and to'the outer surface of the inner sleeve. The insert is then forced between the sleeves and the adhesive is actlvated to bond the insert to the sleeves. Desirably, the insert is .
' compressed to a thickness of between about 45 and 55 percent ~
of its unc~mpressed thickness. For many applications, it is ~-desirable that the axial length of the insert as compared to its thickness be a ratio in excess of 12 For a better understanding of the present invention, ' together with other and further ob,~ects thereof, reference is had to the following description taken in connection with the ... .. .
' accompanying drawings, and its scope will be pointed out in the ' appended claims.
,`.1 . .
In the drawings: ~' Figure 1 is a fragmentary, perspective view of one .~. : . .
type of tandem suspension assembly which embodies the present invention; ' '- ' Figure 2 is a cross sectional view of a beam center ... ; .. . .
;'',!, ' bushing according to this invention, showing the bushing in a ~'~ normal, unloaded state; ' '-~`1 . . . . . .
~~ ' Figure 3 is a cross sectional view similar to Figure ~
,,, : ~, . .
'~ 2, but showing the bushing in one mode of conical stress;
Figure 4 is a cross sec'tional view similar to Figure
2, but showing the bushing in another mode of conical stress;
... , .
'l ~ Figure 5 is a schematic view of a tandem suspension '~' ' assembly showing the front axle and its wheel riding over a , .
~'1 ' bump.
Referring now to the drawing, and particularly to Figure 1, there is illustrated one type or style of ~andem . . , .: :
_5-: : :
:.. , . . ~ . .. . .. . . . .
. ~ , .. , . , . .. ", i3~Z7 suspension assembly 10 which is particularly suitable for heavy duty trucks and the like. The assembly 10 comprises a pair of parallel equalizing beams 11 and 12 which carry bush-ings 13 and 14 at their ends. End brackets 15 and 16 respect-ively connect the bushings 13 and 14 to a pair of spaced, . .
parallel cross axles 17 and 18. There is prbvided a center bushin~ 19 at the midportion of each equalizing be~m 11 and 12 and each bushing 19 is connected to a spring saddle 20 in a manner which wil] hereinafter become apparent. ~ach spring saddle carries a leaf spring 21 or other springin~ device, such ( as an air bag, rubber shear, or rubber pad, and each leaf spring - 21 is provided with spring hangers ?2 which support the truck body. Although leaf springs a~e illustratedj as was noted above~
the invention includes the use of other spring means between the truck body and the unsprung mass. To prevent axle rotation due - to driving and braking forces, torque rods~23 are provided.
Referring now in greater detail to the beam center bushings l9j each bushing 19 includes an inner cylindrical sleeve 24 which may have an end plate 25 closing one end there-` 20 of. A cross tube 34 (Figure 1) is received wikhin the inner -, . . . . .
sleeves of the bushings 19 to thereby connect the equalizing beams The ends of the inner sleeve 24 are mounted in aligned .:':1 .
apertures 26 and 2~, wh-Lch are respectively provided in depend-ing legs 29 and 28 of each spring saddle 20. Each bushing 19 ~l 25 also includes an outer cylindrical sleeve 30 and a tubular, ;` . .
~ ~ cylindrical, elastomeric insert 31 positioned between the .... . .
sleeves.
The insert 31 is sub~ected to stresses caused by the ~, .
;i relative movement of the inner and outer sleeves and their associated parts. One common stress situatlon is illustrated ,, . :i .
. . ' , , .
,...... :.
.; . .
: .. ' :
., .~; . ,~ . , . .,. . . :
: . . .
,~ . .. . . .
'3~
1~63627 '~ in Figures 3 and 4 and includes the application of conical stre~ses to the rubber insert 31 as the imaginary perpendi~
cular planes 32 and 33 of the inner and outer sleeves 24 and 30 become misaligned. Such misalignment may occur if the vehicle encounters a bump in the road, which causes the equal-izing beam 11 and the beam center bushing 19 to be raised ' relative to the other beam center bushing. This is illustrated ~-~
" in Figure 5. Substantially more conical stress occurs when ' the vehicle turns a corner. ; '-Prior art beam center bushings have failed after relatively short stress cycles. The life of the bushings '' according to this invention is greatly increased by adhesively bonding the insert 31 to the inner and outer sleeves 24 and 30.
According to one aspect of the present inventiong the insert is aIso compressed by swaging the outer sleeve radially inwardly ' and/or by expanding the inner sleeve radially outwardly.' '' A bushing according to this aspect of the invention ,. . . .
may be fabricated by coating the outside surface of the sleeve 24 w1th an adhesive and coating the insert surface of the sleeve 30 with an adhesive. The sleeves are placed in a mold and rubber is in~jected betwéen the sleeves. The rubber is then cured to i establish adhesion. However, during the cure, the rubber ex~
. ~ .
pands upon 'being heated and bonds itself to the adlacent sleeve surfaces. Upon cooling, shrinkage obtalns, but the rubber is held 'by the bond against contracting, thereby establishing ten-sile stresses within the rubber To eliminate tensile stresses, I ~ and to establish compressive stresses within the ru'b'ber, either '' the outer sleeve 30 i5 radially compressed by swaging or the ~ ~' innèr sleeve 24 i5 radlally expanded. There~ore~ depending upon ~ '' ' 30 the ~inal desired dlmension, the sleeve 30 would be made over-'! .
.~(, . . . ":
'l -7-. ( , ' .
. " , . .' ~ D-5~(3~
-, .
16~636Z7 sized or the sleeve 24 would be made undersized. Furthermore, in those instances where conical stress is high, the axial length of the insert as compared to its thickness is desirably a ratio in excess of 12:1. The insert 31 includes annular axially facing end surfaces which pro~ect axially beyond the available space between the inner and outer sleeves. As shown in Figures 2, 3 and 4, these end faces are each unconstrained both axially by the legs 29 and 28 and radially by the outer sleeve 30.
According to another aspect of thls invention? a con-ventional post bonding technique may be employed to place the insert in a state of compression and to adhesively bond the -`~ insert between the inner and outer sleeves, for instance see -, U.S. Patent 3,387,839. The elastomeric insert is premolded and . . . - .
has a wall thickness which exceede the radial SpaGe between the ~`; inner and outer sleeves by an amount which corresponds to a .,,$ , desired degree of compression of the insert. The outer surface ~f the inner sleeve and the inner surface of the outer sleeve ~ , ... .
'i~ are coated with a heat activated adheslve. The insert is then forced between the sleeves and the adhesive is heat activated to bond the insert to the sleeve.
Prior art beam center bushings include elastomeric ingerts which are under compression but which are not adhesively ,, .
~`~ bonded to their sleeves. Those bushings have been tested by sub~ecting them to accelerated forces and articulation similar to that received in field use. The mode of failure is very ~; similar to the pattern observed from field failures. The test results indicate that beam center bushings produced in accord-~` ance with this invention should last three to Eour times the s 30 life in fie1d use over current production of non-adhesivel~
bonded bushings.
. i .
; .
" . . .,' . ' '-., ,,. , . :
, ': ,,, : ' ,,:, , . ' . While there have been described what are at present considered to be the preferred embodiments and aspects of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made there-in without departing from the invention, and it is intended, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit and scope .
~ of the invention.
, .~, . .~ ' .', . ' ' ~
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. ~, . .
.,,~, , ,1 , , '.~,i .
i : ' ,'~"~, : ' :.
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. . ; . ; . , .. , . . : . ,, . ,; ,,.
, . .. . . .. . . . . . .. . .
... , .
'l ~ Figure 5 is a schematic view of a tandem suspension '~' ' assembly showing the front axle and its wheel riding over a , .
~'1 ' bump.
Referring now to the drawing, and particularly to Figure 1, there is illustrated one type or style of ~andem . . , .: :
_5-: : :
:.. , . . ~ . .. . .. . . . .
. ~ , .. , . , . .. ", i3~Z7 suspension assembly 10 which is particularly suitable for heavy duty trucks and the like. The assembly 10 comprises a pair of parallel equalizing beams 11 and 12 which carry bush-ings 13 and 14 at their ends. End brackets 15 and 16 respect-ively connect the bushings 13 and 14 to a pair of spaced, . .
parallel cross axles 17 and 18. There is prbvided a center bushin~ 19 at the midportion of each equalizing be~m 11 and 12 and each bushing 19 is connected to a spring saddle 20 in a manner which wil] hereinafter become apparent. ~ach spring saddle carries a leaf spring 21 or other springin~ device, such ( as an air bag, rubber shear, or rubber pad, and each leaf spring - 21 is provided with spring hangers ?2 which support the truck body. Although leaf springs a~e illustratedj as was noted above~
the invention includes the use of other spring means between the truck body and the unsprung mass. To prevent axle rotation due - to driving and braking forces, torque rods~23 are provided.
Referring now in greater detail to the beam center bushings l9j each bushing 19 includes an inner cylindrical sleeve 24 which may have an end plate 25 closing one end there-` 20 of. A cross tube 34 (Figure 1) is received wikhin the inner -, . . . . .
sleeves of the bushings 19 to thereby connect the equalizing beams The ends of the inner sleeve 24 are mounted in aligned .:':1 .
apertures 26 and 2~, wh-Lch are respectively provided in depend-ing legs 29 and 28 of each spring saddle 20. Each bushing 19 ~l 25 also includes an outer cylindrical sleeve 30 and a tubular, ;` . .
~ ~ cylindrical, elastomeric insert 31 positioned between the .... . .
sleeves.
The insert 31 is sub~ected to stresses caused by the ~, .
;i relative movement of the inner and outer sleeves and their associated parts. One common stress situatlon is illustrated ,, . :i .
. . ' , , .
,...... :.
.; . .
: .. ' :
., .~; . ,~ . , . .,. . . :
: . . .
,~ . .. . . .
'3~
1~63627 '~ in Figures 3 and 4 and includes the application of conical stre~ses to the rubber insert 31 as the imaginary perpendi~
cular planes 32 and 33 of the inner and outer sleeves 24 and 30 become misaligned. Such misalignment may occur if the vehicle encounters a bump in the road, which causes the equal-izing beam 11 and the beam center bushing 19 to be raised ' relative to the other beam center bushing. This is illustrated ~-~
" in Figure 5. Substantially more conical stress occurs when ' the vehicle turns a corner. ; '-Prior art beam center bushings have failed after relatively short stress cycles. The life of the bushings '' according to this invention is greatly increased by adhesively bonding the insert 31 to the inner and outer sleeves 24 and 30.
According to one aspect of the present inventiong the insert is aIso compressed by swaging the outer sleeve radially inwardly ' and/or by expanding the inner sleeve radially outwardly.' '' A bushing according to this aspect of the invention ,. . . .
may be fabricated by coating the outside surface of the sleeve 24 w1th an adhesive and coating the insert surface of the sleeve 30 with an adhesive. The sleeves are placed in a mold and rubber is in~jected betwéen the sleeves. The rubber is then cured to i establish adhesion. However, during the cure, the rubber ex~
. ~ .
pands upon 'being heated and bonds itself to the adlacent sleeve surfaces. Upon cooling, shrinkage obtalns, but the rubber is held 'by the bond against contracting, thereby establishing ten-sile stresses within the rubber To eliminate tensile stresses, I ~ and to establish compressive stresses within the ru'b'ber, either '' the outer sleeve 30 i5 radially compressed by swaging or the ~ ~' innèr sleeve 24 i5 radlally expanded. There~ore~ depending upon ~ '' ' 30 the ~inal desired dlmension, the sleeve 30 would be made over-'! .
.~(, . . . ":
'l -7-. ( , ' .
. " , . .' ~ D-5~(3~
-, .
16~636Z7 sized or the sleeve 24 would be made undersized. Furthermore, in those instances where conical stress is high, the axial length of the insert as compared to its thickness is desirably a ratio in excess of 12:1. The insert 31 includes annular axially facing end surfaces which pro~ect axially beyond the available space between the inner and outer sleeves. As shown in Figures 2, 3 and 4, these end faces are each unconstrained both axially by the legs 29 and 28 and radially by the outer sleeve 30.
According to another aspect of thls invention? a con-ventional post bonding technique may be employed to place the insert in a state of compression and to adhesively bond the -`~ insert between the inner and outer sleeves, for instance see -, U.S. Patent 3,387,839. The elastomeric insert is premolded and . . . - .
has a wall thickness which exceede the radial SpaGe between the ~`; inner and outer sleeves by an amount which corresponds to a .,,$ , desired degree of compression of the insert. The outer surface ~f the inner sleeve and the inner surface of the outer sleeve ~ , ... .
'i~ are coated with a heat activated adheslve. The insert is then forced between the sleeves and the adhesive is heat activated to bond the insert to the sleeve.
Prior art beam center bushings include elastomeric ingerts which are under compression but which are not adhesively ,, .
~`~ bonded to their sleeves. Those bushings have been tested by sub~ecting them to accelerated forces and articulation similar to that received in field use. The mode of failure is very ~; similar to the pattern observed from field failures. The test results indicate that beam center bushings produced in accord-~` ance with this invention should last three to Eour times the s 30 life in fie1d use over current production of non-adhesivel~
bonded bushings.
. i .
; .
" . . .,' . ' '-., ,,. , . :
, ': ,,, : ' ,,:, , . ' . While there have been described what are at present considered to be the preferred embodiments and aspects of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made there-in without departing from the invention, and it is intended, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit and scope .
~ of the invention.
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Claims (7)
1. A tandem suspension assembly for heavy duty trucks and the like, comprising, (a) a pair of parallel equalizing beams;
(b) support means at the end of each beam;
(c) end brackets connected to each support means; a pair of spaced, parallel cross axles mounted on said end brackets;
(d) a center bushing at the midportion of each equalizing beam; and (e) bracket means connected to each equalizing beam by its center bushing; each said center bushing comprising an inner cylindrical sleeve, an outer cylindrical sleeve, and a tubular, cylindrical, elastomeric insert positioned between said sleeves and being adhesively bonded thereto, said insert having a first portion occupying substantially all of the available space between said inner and outer sleeves, said insert having a second portion comprising annular axially facing end surfaces, said end surfaces each extending axially beyond said available space and being unconstrained both axially and radially under all loading conditions, and said first portion of said insert being in a state of radial compression.
(b) support means at the end of each beam;
(c) end brackets connected to each support means; a pair of spaced, parallel cross axles mounted on said end brackets;
(d) a center bushing at the midportion of each equalizing beam; and (e) bracket means connected to each equalizing beam by its center bushing; each said center bushing comprising an inner cylindrical sleeve, an outer cylindrical sleeve, and a tubular, cylindrical, elastomeric insert positioned between said sleeves and being adhesively bonded thereto, said insert having a first portion occupying substantially all of the available space between said inner and outer sleeves, said insert having a second portion comprising annular axially facing end surfaces, said end surfaces each extending axially beyond said available space and being unconstrained both axially and radially under all loading conditions, and said first portion of said insert being in a state of radial compression.
2. A tandem suspension assembly according to claim 1, wherein one of said sleeves is radially deformed substantially along its entire axial length thereby placing said insert under radial compression.
3. A tandem suspension assembly according to Claim 1, wherein the wall thickness of said insert is com-pressed to a degree which at least removes the shrinkage stresses.
4. A tandem suspension assembly according to Claim 1, wherein the axial length of the insert as compared to its thickness is a ratio in excess of 12:1.
5. A tandem suspension assembly according to Claim 1, said inner sleeve being expanded to a state of ten-sion, and said insert being in a state of compression.
6. A tandem suspension assembly according to Claim 5, wherein the wall thickness of said insert is com-pressed to a degree which at least removes the shrinkage stresses.
7. A tandem suspension assembly according to Claim 5, wherein the axial length of said insert as compared to its thickness is a ratio in excess of 12:1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US68003476A | 1976-04-26 | 1976-04-26 | |
| DE19777711806 DE7711806U (en) | 1976-04-26 | 1977-04-15 | Double axle arrangement for trucks |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1063627A true CA1063627A (en) | 1979-10-02 |
Family
ID=25947993
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA273,136A Expired CA1063627A (en) | 1976-04-26 | 1977-03-03 | Tandem suspension assembly bushing |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS52131319A (en) |
| AU (1) | AU510073B2 (en) |
| CA (1) | CA1063627A (en) |
| FR (1) | FR2349466A1 (en) |
| GB (1) | GB1571692A (en) |
| SE (1) | SE7704709L (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2503977A1 (en) * | 1981-04-10 | 1982-10-15 | Radiotechnique Compelec | Multiple printed circuit or hybrid circuit substrate mfg. method - allows several small circuit units to be obtained from large sheet by defining boundaries in series of holes of which walls are metallised |
| GB9506805D0 (en) * | 1995-04-01 | 1995-05-24 | Donson Equipment Limited | Vehicle suspension system |
| FR2836525A1 (en) * | 2002-02-25 | 2003-08-29 | Michelin Soc Tech | Fixing procedure for elastomer annular coupling between two tubes consists of compressing outer or inner tube with coupling in place |
| FR2992705B1 (en) * | 2012-06-28 | 2019-05-31 | Anvis Sd France Sas | ELASTIC BEARING FOR MOTOR VEHICLE |
| GB2556252B (en) * | 2015-06-15 | 2020-10-14 | Volvo Constr Equip Ab | Suspension arrangement |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2237575A (en) * | 1937-12-31 | 1941-04-08 | Orpheus F Quartullo | Resilient torsion spring suspension |
| FR957174A (en) * | 1944-07-08 | 1950-02-16 | ||
| US2810587A (en) * | 1953-06-11 | 1957-10-22 | Rockwell Spring & Axle Co | Tandem axle suspension spring seat mounting |
| US2814501A (en) * | 1955-01-20 | 1957-11-26 | Twenty Five Associates Inc | Vehicle tandem axle suspension |
| FR1141007A (en) * | 1956-01-09 | 1957-08-26 | Vehicules Ind Titan Soc Nouv | Suspension for tandem axles, applicable to road vehicles and in particular to trailers and semi-trailers |
| US3129016A (en) * | 1962-01-03 | 1964-04-14 | Hendrickson Mfg Company | Tandem axle suspension |
| US3666335A (en) * | 1970-08-10 | 1972-05-30 | Gen Tire & Rubber Co | Heavy-duty resilient elastomeric bushing |
-
1977
- 1977-03-03 CA CA273,136A patent/CA1063627A/en not_active Expired
- 1977-03-07 GB GB955977A patent/GB1571692A/en not_active Expired
- 1977-03-10 AU AU23112/77A patent/AU510073B2/en not_active Expired
- 1977-04-15 JP JP4344177A patent/JPS52131319A/en active Pending
- 1977-04-25 FR FR7712383A patent/FR2349466A1/en active Granted
- 1977-04-25 SE SE7704709A patent/SE7704709L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| SE7704709L (en) | 1977-10-27 |
| AU2311277A (en) | 1978-09-14 |
| GB1571692A (en) | 1980-07-16 |
| JPS52131319A (en) | 1977-11-04 |
| AU510073B2 (en) | 1980-06-05 |
| DE7711806U1 (en) | 1977-09-04 |
| FR2349466B1 (en) | 1983-06-17 |
| FR2349466A1 (en) | 1977-11-25 |
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