Face seal break-in compound

The present disclosure provides a vehicle assembly, such as a metal face seal, that includes a break-in lubricant compound. The assembly lubricant compound may reduce friction and scoring between contacting surfaces of the assembly, especially during the initial break-in of the assembly. During the initial break-in period, the compound may permit the contacting surfaces of the assembly to seat, or establish a pattern of surface mating, with limited wear and with limited material transfer or scoring.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a vehicle assembly. More particularly, the present disclosure relates to a vehicle assembly, such as a metal face seal, that includes a break-in lubricant compound.

2. Description of the Related Art

Undercarriage assemblies of utility vehicles, such as motor graders, are typically subjected to adverse working conditions and significant loads. For example, metal face seal assemblies used on motor graders may be subjected to extreme temperatures and significant axle loads. Beginning with the initial break-in of the vehicle and throughout the life of the vehicle, these undercarriage assemblies may suffer significant wear. Lubricant compounds may be provided to reduce the wear suffered by the undercarriage assemblies.

SUMMARY

The present disclosure provides a vehicle assembly, such as a metal face seal, that includes a break-in lubricant compound. The assembly lubricant compound may reduce friction and scoring between contacting surfaces of the assembly, such as metallic sealing rings of the metal face seal, especially during the initial break-in of the assembly. During the initial break-in period, the compound may permit the contacting surfaces of the assembly to seat, or establish a pattern of surface mating, with limited wear and with limited material transfer or scoring.

According to an embodiment of the present disclosure, a metal face seal is provided that includes a first metallic sealing ring having a first contact surface and a second metallic sealing ring having a second contact surface, the second contact surface of the second metallic sealing ring configured to contact the first contact surface of the first metallic sealing ring. The metal face seal also includes a lubricant compound located between the first metallic sealing ring and the second metallic sealing ring. The lubricant compound includes less than 20% by weight of a base oil, more than 5% by weight of a GL-5 additive, and a viscosity index modifier.

According to another embodiment of the present disclosure, a vehicle is provided that includes a chassis, at least one ground engaging mechanism configured to support and propel the chassis, an axle configured to drive the at least one ground engaging mechanism, a housing coupled to the chassis, and a metal face seal positioned between the axle and the housing. The metal face seal includes a first metallic sealing ring having a first contact surface and a second metallic sealing ring having a second contact surface, the second contact surface of the second metallic sealing ring configured to contact the first contact surface of the first metallic sealing ring. The metal face seal also includes a lubricant compound located between the first metallic sealing ring and the second metallic sealing ring. The lubricant compound includes less than 20% by weight of a base oil, more than 5% by weight of a GL-5 additive, and a viscosity index modifier.

According to yet another embodiment of the present disclosure, an assembly lubricant compound is provided that includes less than 20% by weight of a base oil, more than 5% by weight of a GL-5 additive, and a viscosity index modifier.

DETAILED DESCRIPTION

FIG. 1provides an illustrative vehicle in the form of motor grader10. Although the vehicle is illustrated and described herein as motor grader10, vehicles of the present disclosure may include, for example, a bulldozer, an excavator, or another vehicle.

Motor grader10includes chassis12. Chassis12supports operator station14and blade16. Operator station14provides a location for a user to operate motor grader10. Blade16is provided for pushing, spreading, and leveling soil and other material.

Motor grader10also includes drive assembly18. Drive assembly18includes at least one ground engaging mechanism20. Ground engaging mechanism20is configured to support and/or propel chassis12. Drive assembly18is coupled to motor22to drive ground engaging mechanism20and, in turn, propel chassis12across the ground. Ground engaging mechanisms20may include wheels, as shown inFIG. 1, or tracks, for example. Drive assembly18may be a tandem assembly, such as the tandem assembly disclosed in U.S. Pat. No. 4,535,860, the disclosure of which is expressly incorporated herein by reference.

Referring next toFIG. 2, drive assembly18of motor grader10further includes housing30and axle32. Housing30of drive assembly18is coupled, directly or indirectly, to chassis12(FIG. 1). Axle32extends through housing30and is rotated by motor22(FIG. 1). Flange34is located at an end of axle32that is opposite from chassis12(FIG. 1). Flange34may be coupled to ground engaging mechanism20(FIG. 1). In operation, as motor22rotates axle32relative to housing30, ground engaging mechanism20coupled to flange34of axle32also rotates to propel chassis12across the ground.

Referring still toFIG. 2, seal40is provided between stationary housing30and rotating axle32, specifically between housing30and flange34of axle32. Seal40serves to prevent debris from entering housing30and lubricating fluid from leaking out of housing30. As shown inFIG. 2, seal40includes two metallic sealing rings,42,42′, and two elastomeric load rings,44,44′, surrounding sealing rings,42,42′. Metallic sealing rings,42,42′, may be constructed of nickel, a nickel alloy, iron, an iron alloy, such as stainless steel or stellite, or another suitable metal, for example. Elastomeric load rings,44,44′, may be constructed of a nitrile polymer, a silicone polymer, or another suitable elastomer, for example. Sealing ring42and load ring44are located adjacent to stationary housing30, while sealing ring42′ and load ring44′ are located adjacent to rotating flange34of axle32. In this embodiment, as axle32rotates relative to housing30, sealing ring42′ rotates against opposing sealing ring42.

To reduce friction and scoring between metallic sealing rings,42,42′, an assembly lubricant compound50may be applied to sealing rings,42,42′. Specifically, compound50may be applied to one or both contacting surfaces,43,43′, of sealing rings,42,42′, respectively. Compound50may be thick enough to reduce friction and scoring between sealing rings,42,42′, while being thin enough to require a reasonable amount of energy to rotate sealing ring42′ against opposing sealing ring42. An exemplary compound50may reduce friction and scoring between contacting surfaces,43,43′, of metallic sealing rings,42,42′, especially during the initial break-in or start-up of rotating axle32. During the initial break-in of rotating axle32, such as the first several hours of operation of motor grader10, compound50may permit metallic sealing rings,42,42′, to seat with limited wear and with limited material transfer or scoring. Seating generally involves establishing a pattern of surface mating by properly aligning contacting surfaces,43,43′, of sealing rings,42,42′, under a load, while scoring generally involves damaging contacting surfaces,43,43′, of sealing rings,42,42′, under a load, such as by transferring metal from one sealing ring42to the other sealing ring42′. Although compound50is described herein as being applied to seal40, compound50may be applied to other assemblies, seals, or moving parts of motor grader10, including other undercarriage assemblies of motor grader10.

Compound50generally includes a base oil, a viscosity index modifier, and an additive. According to an exemplary embodiment of the present disclosure, compound50includes less than 20% by weight of the base oil and more than approximately 5% by weight of the additive, with the viscosity index modifier making up the balance. For example, compound50may include approximately 15% by weight of the base oil, approximately 10% by weight of the additive, and approximately 75% by weight of the viscosity index modifier. The amount of base oil may be varied to alter the consistency of compound50. For example, increasing the amount of base oil from 8% by weight to 15% by weight makes compound50less viscous and easier to apply to sealing rings,42,42′.

The viscosity index modifier of compound50may stabilize the kinematic viscosity of compound50over various temperatures. The viscosity index modifier of compound50may include a polymer and base oil, for example. An exemplary viscosity modifier includes 2-Propenoic acid, 2-methyl-, dodecyl ester, polymer with methyl 2-methyl-2-propenoate (C21H38O4) [CAS No. 30795-64-3] and base oil. More specifically, an exemplary viscosity modifier includes approximately 50 to 100% by weight of 2-Propenoic acid, 2-methyl-, dodecyl ester, polymer with methyl 2-methyl-2-propenoate (C21H38O4) with base oil making up the balance. The base oil used in the viscosity index modifier may include, for example, one or more of the following components: solvent-dewaxed heavy paraffinic petroleum distillates [CAS No. 64742-65-0]; hydrotreated heavy paraffinic petroleum distillates [CAS No. 64742-54-7]; hydrotreated middle petroleum distillates [CAS No. 64742-46-7]; solvent-dewaxed light paraffinic petroleum distillates [CAS No. 64742-56-9]; solvent-refined heavy paraffinic petroleum distillates [CAS No. 64741-88-4]; solvent-refined light paraffinic petroleum distillate mineral oil [CAS No. 64741-89-5]; and other suitable base oils.

The additive of compound50may encourage compound50to stick to sealing rings,42,42′. An exemplary additive is a GL-5 additive. As used herein, a “GL-5 additive” is a substance that, when added to a base oil, produces a gear oil that meets and/or exceeds performance requirements of the American Petroleum Institute's (API) Category GL-5 service. Current performance requirements for API Category GL-5 service are set forth in Standard Specification D7450-08 published by the American Society for Testing and Materials International (ASTM International) and entitled “Standard Specification for Performance of Rear Axle Gear Lubricants Intended for API Category GL-5 Service,” which is attached hereto as Appendix A. Applicable test methods are also generally available from ASTM International.

An exemplary GL-5 additive includes the components set forth in Table 1 below.

Compound50may have a boiling point that exceeds 500° F. (260° C.). Compound50may have a specific gravity between approximately 0.8 and 0.9.

An exemplary method of the present disclosure involves applying compound50to sealing rings,42,42′, during the initial break-in or start-up of motor grader10, as shown inFIGS. 1 and 2. First, compound50is applied to sealing rings,42,42′. Specifically, compound50is applied to one or both contacting surfaces,43,43′, of sealing rings,42,42′, respectively. Compound50may have the consistency of honey such that compound50is spreadable yet clings onto sealing rings,42,42′. Next, sealing ring42and load ring44are aligned with stationary housing30. Then, sealing ring42′ and load ring44′ are aligned with rotating axle32. Finally, axle32may be manually rotated relative to housing30to further spread and disperse compound50across contacting surface43of sealing ring42and contacting surface43′ of sealing rings42′.

EXAMPLE

An experiment was conducted to evaluate the effectiveness of various lubricant compounds during the initial break-in or start-up process. Each lubricant compound was applied to numerous seals, and the seals were tested to simulate break-in.

Compound 1 consisted of a transmission and hydraulic oil that includes approximately 79-85% by weight of a base oil, approximately 10-15% by weight of a poly-methacrylate viscosity modifier, and approximately 5-6% by weight of an additive containing zinc dialkyldithiophosphate [CAS No. 84605-29-8].

Compound 2 consisted a lubricant compound that includes approximately 8% by weight of a base oil, approximately 85% by weight of a viscosity index modifier, and approximately 7% by weight of the additive package used in Compound 1.

Compound 3 consisted of a lubricant compound, and specifically Compound 3 consisted of an exemplary compound50as described above. Compound 3 included approximately 15% by weight of a base oil, approximately 10% by weight of a GL-5 additive, and approximately 75% by weight of a viscosity index modifier. The base oil included hydrotreated heavy paraffinic petroleum distillates [CAS No. 64742-54-7]. The GL-5 additive had a composition as set forth in Table 1 above. The viscosity index modifier included approximately 50 to 100% by weight of 2-Propenoic acid, 2-methyl-, dodecyl ester, polymer with methyl 2-methyl-2-propenoate (C21H38O4) [CAS No. 30795-64-3] with base oil making up the balance.

As a baseline test, approximately 2 cubic centimeters of Compound 1 was applied to each of seven seals. The metallic sealing rings of the various seals were constructed of an iron-based stellite alloy. One metallic sealing ring of each seal was immediately rotated at 200 rpm relative to an adjacent stationary metallic sealing ring of the seal. Three of the seven seals, or 43% of the seals, developed leaks within thirty minutes.

To evaluate the performance of the lubricants during break-in, approximately 2 cubic centimeters of lubricant was applied between the metallic sealing rings of each seal. Within each category, multiple seals were evaluated. The metallic sealing rings of the various seals were constructed of an iron-based stellite alloy. After the lubricant was applied, one metallic sealing ring of the seal was rotated relative to an adjacent stationary sealing ring of the seal for five minutes in each gear. Specifically, one metallic sealing ring was rotated relative to the other for five minutes at each of the following speeds: 17 rpm (first gear), 23 rpm (second gear), 33 rpm (third gear), 45 rpm (fourth gear), 68 rpm (fifth gear), 95 rpm (sixth gear), and 130 rpm (seventh gear). After simulating break-in of each seal, the sealing ring was subjected to rotation at 200 rpm for thirty minutes. The experimental results are set forth in Table 2 below.

Notably, even though only 11% of the seals tested with Compound 1 failed, 89% of the seals showed signs of impending score, indicated by a rough torque trace during testing. A higher percentage of seals failed with Compound 2, the lubricant compound, than with Compound 1, the hydraulic oil. Surprisingly, none of the seals tested with Compound 3, another lubricant compound, failed, and only 18% showed signs of impending score.

While various embodiments of this invention are exemplified and described, embodiments of the present invention can be further modified within the spirit and scope of this disclosure. This application therefore covers variations, uses, or adaptations of the invention using its general principles. Further, this application covers such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the elements of the appended claims.