CA1081293A

CA1081293A - Bogie pad and crawler type vehicle having same

Info

Publication number: CA1081293A
Application number: CA298,988A
Authority: CA
Inventors: James R. Sturges; Robert J. Purcell
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1977-04-07
Filing date: 1978-03-15
Publication date: 1980-07-08
Also published as: MY8300144A; IT7821710A0; IT1093948B; GB1579048A; JPS6124231B2; DE2814466C2; HK73083A; JPS53126637A; DE2814466A1

Abstract

BOGIE PAD AND CRAWLER TYPE VEHICLE HAVING SAME
Abstract of the Disclosure A unitary bogie pad has a base portion, an inter-mediate portion, and a cap portion each of a generally round horizontal cross sectional configuration. The base portion is of a columnar configuration, the intermediate portion has outer annular walls sloping generally inwardly, and the cap portion is of a generally domed configuration.

Description

~)8~Z~3 Heretofore utilized bogie pads, particularly those utilized in crawler vehicles, were generally made of rubber and had an operational life less than desirable. After con-siderable research, it was discovered that the configuration of the undeflected bogie pad was a determing factor in its life period.
During use of the bogie pads, internal triaxial stresses are subjected onto the pad. It has been discovered that these stresses could be moved within and be minimised by changing the configuration of the bogie pad.
Bogie pads are subjected to a great deal of abuse, adverse conditions, and extremely heavy impacts. I~ is desirable to provide a bogie pad which can withstand these adverse operating conditions while remaining operable for longer periods of time~
According to one aspeat of the present invention, there is provided a unitary resilient support pad formed by a solid block of resilient material having an upright axis, a base portion, an intermediate portion, and a cap portion each having cross sections normal to the axis with continu-ously rounded peripheries, the base portion being of an upright columnar configuration and defining a peripheral wall surface, the intermediate portion having an outer annular wall surface sloping generally inwardly toward the axis from an intersection with the peripheral wall surface of the base portion to an intersection with the cap portion, the cap portion being of a general domed coniguration, and the support pad being of a construction sufficient for deflection of s~bstantially the entire cap portion to a substantially planar surface.
The invention also relates to a crawler type vehicle ~ - 2 -~8~3 comprising: a frame; an arm pivotally connected to the frame; a plate releasably connected to one of the frame and the arm; and a resilient support pad bon~ed to khe plate and disposed at a location between the frame and the arm, the support pad formed by a solid block o~ resilient material having an upright axis, a base portion, an intermediate portion, and a cap portion each having cross sections noxmal to the axis with continuously rounded peripheries, the base portion being of an upright columnar configuration and defining a peripheral wall surface, the intermediate portion having an outer annular wall surface sloping generally inwardly toward the axis from an inter-section with the peripheral wall surface of the base portion to an intersection with the cap portion, the cap portion being of a general domed configuration, and the support pad being of a construction sufficient for deflection of substantially the entire cap portion to a substantially planar surface.
Some examples of bogie pads constructed in accordance with the invention, and of crawler vehicles fitted with such pads, are illustrated in the accompanying drawings, in which:-Fig. 1 is a diagrammatic view of a portion of one crawler vehicle;
Fig. 2 is a diagrammatic frontal view of a bogie pad in an unload position Fig. 3 is a diagrammatic top view of a bogie pad in an unload position;
Fig. 4 is a diagrammatic frontal view of a bogie pad system;

- 2a -id~

~8~zg3 Fig. 5 is a di~gramrnatic frontal view of a bogie pad in a partially loaded condition;
Fig. 6 is a diagrammatic frontal view of a bogie pad in a fully loaded condition;
Fig. 7 is a bogie pad system ln a partially loaded condition; ; ;
Fig. 8 is a bogie pad system in a fully loaded condition; and, ~
Fig. 9 is a load-deflection curve of the bogie pad. ~ ~ -Detailed Description of Embodiments of the_Invention i Referring to Fig. 1, a crawler type vehicle 10, for example a crawler type tractor, has a continUPus track 12 for locomotion. The vehicle 10 has a frame 14 and at least one bogié assembly 16 associated with each track 12. The bogie assembly 16 includes a bogie arm 18 pivotally connected at one end to the frame and has a track roller system 20 connected at the other end. The arm 18 is pivotally ~ovable relàtive to the frame for supporting the associated track 12 with the rollers 20 during movement of the track 12 toward ~o and from the frame 14, as 1s well known in the art.

ïZ93 By the term rame 14, as used herein, it is meant any supporting structure suitable that is maintained at a preselected location relative to the vehicle 10.
At least one unitary bogie or resilient support pad 22 is fixedly connected to the bogie arm 18, as shown in bogie assembly 16 or to the frame 14 as shown in bogie assembly 16'. The bogie pad 22 extends outwardly from the connecting structure 14 or 18 and is positioned at a location between the frame 14 and bogie arm 18 and is of a size sufficient for contacting the other structure 14 or 18 in response to pivotal movement of the bogie arm 18 toward the frame 14 for controllably damping the movement of said arm 18.
Referring to Figs. 2 and 3, the bogie pad 22 has a base portion 24, an intermediate portion 26, and a cap portion 28. Each of the portions 24, 26, 28 are of a generally round horizontal cross sectional configuration, as ~;
can be seen in Fig. 3, with said configurations preferably being circular. It is contemplated that the term ~"generally round" as used herein embraces elliptical cross sections.
The base portion 24 has a base surface 25 connected to a respective frame 14 or 18 bogie arm 18. The base surface 25 can be directly connected to the frame 14 or bogie arm 18 by bonding in any suitable manner or can be indirectly connected to the frame 14 or bogie arm by bonding the bogie pad 22 to a supporting plate 30 and connecting the supporting plate 30 to said frame 14 or bogie arm 18 by any suitable fastening means 32, as shown in Fig. 4.
The intermediate portion 26 has outer annular walls 34 which slope generally inwardly forming a frustum in the-undeflected condition of the pad 22. ~lhe cap portion 28 is of a generally domed configuration and has a general ' al~cua~e o~lt~r sur~ace.
Lines "a" and "b" have been des-l~nate~ in Fig. 2 to indicate the lines of demarcation between the various portions, 24, 26, 2~.
Referring to Fig. 4 ~ a bogie pad system 36 is shown wherein a bogie pad 22', 22 " is positioned on a respective frame 14 and bogie arm 18 at locations where one bogie pad 22' contacts the other ad~acent bogie pad 22"
during povotal movement of the bogie arm 18. In the bogie pad system 36, the pads 22'~ 22'' are of a configuration and are positioned at locations sufficient for initial].y contacting one another at locations between the center "c" o each arcuate outer surface and the outer edge 38 of the cap portion ~.
28 in response to pivoting of the bogie arm 18. This con-struction of a pad 22 and positioning is also maintained where only a single pad 22 is utilized, as shown in Fig. 1. The initial contact point of the pad is likewise spaced from the , center "c" and the outer edge portion 38 of the cap portion 28.
By so locating the initial contacting point, the operational life of the pad 22 is markedly increased by assuring against the introduction of additional shear stresses in the pad in response to initially contacting an intermediate portion 26 of the pad 22 or the outer edge portion 38 of the cap portion 28. As set forth above, the bogie arm 18 is pivotally movable and the pad pathway is arcuate. Therefore, during design of the pad 22, the radius of the arc must be ~;
taken into consideration in order to assure the preselected initial contacting polnt of the pad 22.
The outer surface of the dome shaped cap portion 3U of the bogie pad 22 can be defined by an arc of a single ~.
- , .

. ~-. . ~ . . , '~3 radiu~, as in pacl 22' or Or a plurality of radii, as in pad 22" .
The base portion 24 of the bogl.e pad 22 has a preselcted base surface 25 area based upon the total weight of the vehicle 10. The total base area of each pad 22 is . defined by the expression Area = T
C
where C = The nominal compressive stress o~ the rubber in the range of about 3500 to about 8300 Kilo-pascals. '~
T = Total weight ~f vehicle upon which pad is expected to be used.
A pad 22 of greater area is undesirable owing ~o the facts that material and space on the vehicle will be wasted. A pad 22 of lesser area is undesirable owing to the facts that undesirable pressures will be subjected onto the pad 22 and the operationsl life of the resultant pad 22 will be less than desirable.
At a nominal compressive stress "C" less than about 20 3500 Kilopascals the bogie pad ls undesirably large in size and wastes space on the vehicle and causes associated equipment to be unnecessarily large which also represents waste. At a "C" greater than 8500 Kilopascals the bogie pad is subjected to stresses of a suf~iciently high magnitude as to cause the ;
operational life of the resultant pad to be undesirably t short.
The base portiorl 24 also should be constructed ..
w~th a height "Hb" ln the range of about 2 to about 15 mm.
At lesser heights of the base portion 24, the pad will ~`~
30 undesirably hlnge at a location within the lntermediate ~ ~;

;~3 portion 26 wh:;ch will in~roduce undesirable stresses in the -pad 22 and result ~n an undesirable operational life. At greater heights of the base portion 24, the pad ~111 u~desir-ably hinge within the base portion 24 which will introduce undesirable stresses in the pad 22 and result in an undesirable operational life.
With a base height maintained as set forth in the above citied equation, the hinging of the pad will be maintained at the connection of the base surface 25 to a frame 14 or bogie arm 18.
The overall height of the pad 22 is based on the compression of the pad. It is preferred that the bogie pad have maxi~um compression value for the intended use in a range of about 1/2 inch to about 3 inches. Maximum compression values less than about 1/2 inch are undeslrabIe because the bogie arm will not have sufficient damped travel. Maximum compression values greater than about 3 inches are undesirable because the vehicle will have undesirable working tool stability. The mximum compression value is preferably ~0 about 1-1/2 inches. The overall height of the bogie pad is .
constructed so that the maximum compression travel is in the range of 20% to 40% of the overall Height Ht.
Referring to Fi~s. 5 and 7, the pad or pads 22 are preferably of a dimension sufficient for deflection of s-ubstantially the entire cap portion 28 to a substantially planar surface in the installed position of the pads 22 on a standing vehicle ~ith said pads supporting the vehicle -weight. Under these stable load Conditions~ it will be rioticed the the base portion 24 has hingedly moved outwardly and that the intermediate portion 26 has moved out~ardly.

'' ' " ,' . ~ .

, . ~ , , _7_ Referring to Figs. 6 and 8, the pad or pads 22 are sub~ected to the max~mum expected load and the base and intermediate portions 24, 26 are further outwardly extending.
The pads 22 are preferably formed of natural rubber havin~ carbon black therein and being substantially free of reinforcing elements of other material. By the term , , ' reinforcing elements of other ma~erials it is meant mechanlcal ;~
reinforcing materials sucll as wire, cords, meshes, and the like, and does not refer to chemical reinforcing elements '10 such as the carbon black and other chemical binders used in , the forming of rubber.
Referring to,~ig. 9, it can be seen that the pad 22 of the above described construction has load deflection properties at which the load-deflection curve of the pad at maximum expected load is substantially vertical. ,~
, I~ the example pad, hereinafter described, the static load on the pad is about 20,000 lbs. and the maximum expected load is 160,000 lbs. It should be noticed that the d~lection of the,pad between the static and maximum load is ;
about l inch with a 1-1/2 inch maximum compression.
This is particularly significant where'it is realized that the unique construction of the pad of this invention minimizes load stresses within the pad'to the extend that the pad has une~pected operational life while ~ , being subjected to 40% and greater deflection. He~tofore'~, utilized pads of other construction would experience drasti-cally reduced operational life at such heavy loads and great deflections.
'.

' . .

.~

Z~33 The followin~ is a preferred example bogie pad 22 of this invention.

.
PREFERRED MATERIAL
FORMULATION
BRAND NAME PARTS
PREFERRED INGREDIENT AND SOURCE (BY WEIGHT) NO. 1 Ribbed Smoked Sheet ~ lCO.O
FEF Carbon Black STATEX M- 70.0 COLUMBIAN CARBON CO.
PROCESS OIL CIRCO LIGHT RUBBER
PROCESS OIL- 10.0 SUN OIL CO.
STEARIC ACID STEARIC ACID 2.0 , : C. P. HALL CO.
ZINC OXIDE PROTOX 166 5.0 . - . NEW JERSEY ZINC CO.
SULFUR SPIDER BRAND 2.75 ~ : .
~ OLIN-MATHLESON CO.
ANTIOXIDANT - OCTAMINE 1.0 ~ UNIROYAL CHEMICAL DIV. . . ~; -ANTIOZONANT ~ : FLEXZONE 3C : 1.0 ~ UNIROYAL CHEMICAL DIV~
ACCELERATOR SANTOCURE MOR- . 0.90 . MONSANTO CO.
PRE-VULCANIZATION SANTOGARD PVI 0~25 ~ .,.
MONSANTO CO.
INHIBITOR

_; . , . . :

, ; ~, ' .

: .

.

PROCESSIN(~
A. ~IIXING
1. 0.5 PARTS PEPTIZER ENDOR - E.I. DU PO~T PER }IUNDRED RUBBER FOR
PREMASTICATION.

2. NO OILS OR PROCESSINC AIDS EXCEPT AMOUNT OF OIE SHOWN IN
FOR~'ULATION.

3. COMPOUNDING INGREDIENTS ARE W~LL DISPERSED.

4. A TWO STAC,E MIXING PROCEDURE. ~ALL IN~REDIENTS EXCEPT CURATIVE
(SULFUR, SANTOCURE MOR, AND SANTOG~RD)ARE MIXED INTO THE
PRE~STICATED RSS NO. 1 AND C~OLED. THE CURATIVE ARE ADDED IN
A SECOND STEP IN A MIXER.
B. MOONEY VISCOSITY AND SCORCH TIME OF MIXED STOCK PRIOR TO MOEDING:
VISCOSITY - MLl + 4 - 100C (212F) 65 SCORCH - (ML) 135C (275F) C. RHEOMETER CURED CHAR~CTERISTICS (ASTM D2084) ]. PLATEN TEMPERATURE - OSCILLATION - 1.67Hz (100 cpm) 148C (298F) CHARTMOTOR - 60 MIN.
PREHEAT TIME -O SEC.
1. M~ (MIN. TOR~UE) 1.0 Nm (8.4 LB. IN) .
Z. ~1 (MAX. TORQUE) 4.7 Nm (41.6 LB. IN) 3. T2 (SCORCH TIME) 8.7 MINUTES
- 4. Tc95 (CURE TIME) 20.1 MINUTES
~ .:
2. PLATEN TEMPERATURE - OSCILI.ATION - 1.67 Hz (lOO cpm) 162C (324F) C}~RTMOTOR - 60 MINUTES
PREHEAT TIME - 0 SEC.
1. ML (MIN. TORQUE) 0.9 Nm (8.1 LB. IN.) 2. MH (MAX. TOROUE) 4.4 Nm (39.2 LB. IN.) -~~~ 3. T2 (SCORCH TI~) 3.7 MINUTES
4. Tc95 (CURE TIME) 8.6 MINUTES

' ' ' ' ' ' :

~ .

`. , ' - .. ...

3`

PROPERTIES
____ ~
1. ~RDNESS (ASTM D2240) 70 SHORE A
2. TENSILE STRENG'~i (ASTM D412) 18.6 MPa (2700 PSI) 3. ELONGATION (ASTM D412) 325%
4. 100% MODULUS (ASTM D412) 4.8 MPa (700 PSI)

5. 300% MODULUS (ASTM D412) 18.6 MPa (2700 PSI)

6. TE~R STRENGTH ASTM (D624-DIEC3 525 N/cm (300 IB/IN) MIN.

7. COMPRESSION SET 25% MAXIMUM
(ASTM D395 - METHOD B) ASTM BUTTONS CURED
30 MIN. AT lh8C

22 HOURS AT 70C (158F)

8. COMPRESSIVE MODULUS ASTM (D575) 2.9 MPa -METHOD A) AT 25~ DEFLECTION (425 PSI)

9. SPECIFIC GRAVITY , 1.165 AIR OVEN AGING (ASTM D573 -70 HOURS AT 70C (158F) 1 HARDNESS CHANGE +IO MAXIMUM
2 TENSI~E CHANGE +20X
3. ELONGATION CHANGE -25% ~XIMUM
4. SURFACE CONDITION NO CRACKS : ' . ' . ' , . ~ .

PREFERRED DI~NSIONS
1. BASE DIAMETER 14.20 IN.
2. TOTAL OVERALL HEIGHT Ht 2.25 IN.
3~ CROWN HEIGHT H .50 IN.
' 4. HEIGHT OF BASE Hb .2~ IN.
5. ANGLE ~ 55 '.' ' ~ '"' ~, ' .
. ~ . . :

.
.

The subject example pad has been tested with 160, 000 pound load . The test example bogie pad has presently been compressed to the maximum design compression ~hrough 2,000,Q00 cycles and remain, iil operat~ng conditlon.

' t . ' ~ ', lQ
.
..

.' - ~ .:

.

~ ~ .
: ' ' , ';
. . . :::
' ' ' '' ' - '.
- . , ' ~ ' . ' .
_12- . ~

: . .. .. , :

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A unitary resilient support pad formed by a solid block of resilient material having an upright axis, a base portion, an intermediate portion, and a cap portion each having cross sections normal to the axis with continuously rounded peripheries, the base portion being of an upright columnar configuration and defining a peripheral wall surface, the intermediate portion having an outer annular wall surface sloping generally inwardly toward the axis from an intersection with the peripheral wall surface of the base portion to an intersection with the cap portion, the cap portion being of a general domed configuration, and the support pad being of a construction sufficient for deflection of substantially the entire cap portion to a substantially planar surface.

2. The support pad of claim 1 wherein the intermediate portion is a frustum and the annular wall surface defines a preselected angle ? of about 55° in vertical cross section with respect to a horizontal plane.

3. The support pad of claim 1 wherein the maximum compression travel is in the range of about 20%
to 40% of the overall height Ht.

4. The support pad of claim 1 wherein each of the base, intermediate, and cap portions has a circular horizontal cross sectional configuration.

5. The support pad of claim 1 wherein the base portion has a bottom surface having a preselected area defined by the expression "Area = ?"
wherein:
C = a constant in a range of about 3,500 to about 8300 kPa.
T = total weight of the vehicle upon which the support pad is to be used.

6. The support pad of claim 1 wherein the substantially entire cap portion is deflected to a substantially planar surface at the installed position of the support pad on a vehicle in a standing mode of operation.

7. The support pad of claim 1 wherein the support pad is of a construction sufficient for providing load deflection properties at which the load deflection curve at maximum expected load is substantially vertical.

8. The support pad of claim 1 wherein the base portion has a height Hb in the range of about 2 mm to about 15 mm.

9. The support pad of claim 1 wherein the base, intermediate and cap portions define an overall height Ht, and the base portion has a preselected height Hb in a range of about 3.5% to about 26% of the overall height Ht.

10. The support pad of claim 9 including a supporting plate, and wherein the base portion has a bottom surface bonded to the supporting plate.

11. The support pad of claim 10 wherein the peripheral wall surface of the base portion remains substantially straight in vertical cross section and pivots at the connection of the peripheral wall surface and the bottom surface in response to the applica-tion of a partial load on the cap portion.

12. A crawler type vehicle comprising:
a frame;
an arm pivotally connected to the frame;
a plate releasably connected to one of the frame and the arm; and a resilient support pad bonded to the plate and disposed at a location between the frame and the arm, the support pad formed by a solid block of resilient material having an upright axis, a base portion, an intermediate portion, and a cap portion each having cross sections normal to the axis with continuously rounded peripheries, the base portion being of an upright columnar configuration and defining a peripheral wall surface, the intermediate portion having an outer annular wall surface sloping generally inwardly toward the axis from an intersection with the peripheral wall surface of the base portion to an intersection with the cap portion, the cap portion being of a general domed configuration, and the support pad being of a construction sufficient for deflection of substantially the entire cap portion to a substantially planar surface.

13. The crawler type vehicle of claim 12 wherein the intermediate portion is a frustum and the annular wall surface defines a preselected angle 0 of about 55° in vertical cross section with respect to a horizontal plane.

14. The crawler type vehicle of claim 12 wherein the maximum compression travel is in the range of about 20% to 40% of the overall height Ht.

15. The crawler type vehicle of claim 12 wherein the base portion has a bottom surface having a preselected area defined by the expression "Area = T" wherein:
C = a constant in a range of about 3,500 to about 8300 kPa.
T = total weight of the vehicle upon which the support pad is to be used.

16. The crawler type vehicle of claim 12 wherein the substantially entire cap portion is deflected to a substantially planar surface at the installed position of the support pad on the vehicle in a standing mode of operation.

17. The crawler type vehicle of claim 12 wherein the support pad is of a construction sufficient for providing load deflection properties at which the load deflection curve at maximum expected load is substantially vertical.

18. The crawler type vehicle of claim 12 wherein the cap portion has a generally arcuate outer surface having a center and an outer edge, the support pad being of a configuration and positioned at a location sufficient for contacting the other of the frame and arm at a location on the cap portion spaced from the center and the outer edge in response to pivoting of the arm.

19. The crawler type vehicle of claim 12 including another resilient support pad con-nected to the other one of the frame and the arm, each of the resilient support pads con-tacting and loading one another in response to pivoting of the arm.

20. The crawler type vehicle of claim 19 wherein the cap portion of each resilient support pad has an arcuate outer surface defining a center and an outer edge and the resilient support pads are of a construction sufficient for contacting the cap portions, one with the other at locations spaced from their respective centers and outer edges in response to pivoting of the arm.

21. The support pad of claim 12 wherein base portion has a bottom surface bonded to the plate.

22. The crawler type vehicle of claim 21 wherein the peripheral wall surface of the base portion remains substantially straight in vertical cross section and pivots at the connection of the peripheral wall surface and the bottom surface in response to the application of a partial load on the cap portion.

23. The crawler type vehicle of claim 12 wherein the base portion is about 9% of the overall height Ht, the intermediate portion is about 68%
of the overall height Ht, and the cap portion is about 23% of the overall height Ht.