News and Articles: CVJ GREASES: MOLYVAN 855 Formulations Found Particularly Advantageous

Before viewing any of the following articles or presentations, please be sure to read the usage statement.

CVJ GREASES: MOLYVAN 855 Formulations Found Particularly Advantageous

By Thomas J. Karol, Ph.D. and Steven G. Donnelly (Manager of Technical Services)

This disclosure relates to a grease composition and particularly an additive formulation designed for the demanding environment of Constant Velocity Universal Joints (CVJ). In front wheel, all wheel, and four wheel drive vehicles, these joints are used to transmit the engine torque to the vehicle wheels. The different type of CVJ designs available today are ball fixed joints, double offset joints, tripod joints, freering tripod joints, cross groove joints and the newly introduced high efficiency compact fixed constant velocity universal joint (introduced by NTN Corporation)¹.

The design and lubrication requirements of constant velocity joints have been described in detail in a number of patent publications (USP 5,207,936; USP 4,840,740; USP 5,487,837; GB 2 255 346 A; EP 0 668 900 B1). Constant velocity joints are generally lubricated with extreme-pressure/antiwear grease. Typically the base grease consists of a mineral oil, lithium soap and/or a urea thickener. Additives such as molybdenum disulfide, sulfur-phosphorus compounds, zinc dialkyldithiophosphates and lead dithiocarbamates have all been used in CVJ greases.

A widely accepted test for this application is the SRV test² to measure friction and wear. The R.T. Vanderbilt Company has found that MOLYVAN 855 is synergistic with zinc O,O-di-C_1-14-alkyl-phosphorodithioate (ZnDTP) or substituted 1,3,4-thiadiazoles, or mixtures thereof, in friction and wear reduction (patent pending). MOLYVAN 855 is an organomolybdenum complex prepared by reacting about 1 mole fatty oil, about 1.0 to 2.5 moles diethanolamine and a molybdenum source sufficient to yield about 0.1 to 12.0 percent of molybdenum based on the weight of the complex. Of particular utility in the thiadiazole chemistry is VANLUBE 871, which is a succinate ester substituted 1,3,4-thiadiazole, but other oil soluble 1,3,4-thiadiazoles may be utilized (such as CUVAN 826, and CUVAN 484) (patent pending).

The most impressive SRV performance data we obtained utilized our patent pending antiwear technology (EP 0 874 040 A1). This combination afforded the lowest coefficient of friction versus the molybdenum dithiocarbamate (MoDTC) and ZnDTP that are typically used in this application. An example of this highly impressive data is Example 1 utilizing a prototype polyurea grease.

Example 1

Tradename	Description	Concentration
MOLYVAN 855	Molybdate	0.66% (528PPM Mo)
VANLUBE 871	Thiadiazole	1.5%
LUBRIZOL 1395^a	ZnDTP	1.0%
OD-9510^b	Bismuth Dithiocarbamate	0.5%

a) Lubrizol 1395 is available from the Lubrizol Corporation.

b) OD-9510 (U.S. Patent 5,840,664) is available from the R.T. Vanderbilt Corporation for evaluation.

The formulation in example 1 may be augmented with boron compounds such as alkyl glycerol borates or alkyl diethanolamide borates, or mixtures thereof as described in U.S. Patent literature.

The following graphs demonstrate the comparison of the disclosure technology to a reference polyurea grease containing a molybdenum dithiocarbamate (MoDTC) and a zinc dithiophosphate (ZnDTP) [Graph 1]. The data shows dramatically improved SRV friction results for our new technology [Graph 2].

Akira Wakita and Keilsuke Sone (both of NTN Corporation), " High Efficiency Compact Fixed Constant Velocity Universal Joints (EBJ)" , SAE Technical Paper 1999-01-0748, reprinted from 1999 Transmission and Driveline Systems Symposium (SP1440), March 1-4. 1999.
ASTM D5707, 50N x 30s, 200 N (slow ramp) x 2h, stroke: 1.00 mm, frequency: 50 Hz.

Use of Information

The information presented herein, while not guaranteed, was prepared by technical personnel and, to the best of our knowledge and belief, is true and accurate as of the date hereof. No warranty, representation or guarantee, express or implied, is made regarding accuracy, performance, stability, reliability or use. This information is not intended to be all-inclusive, because the manner and conditions of use, handling, storage and other factors may involve other or additional safety or performance considerations. The user is responsible for determining the suitability of any material for a specific purpose and for adopting such safety precautions as may be required. R. T. Vanderbilt Company does not warrant the results to be obtained in using any material, and disclaims all liability with respect to the use, handling or further processing of any such material.No suggestion for use is intended as, and nothing herein shall be construed as, a recommendation to infringe any existing patent or to violate any federal, state or local law or regulation.
[ Click to Top of Page ]