Ethyl Petroleum Additives, Inc.

Hiroko Ohtani

Rolfe J Hartley

An effective way is described for overcoming the shudder problem associated with continuous slip torque converter clutches for use in automatic transmissions, especially shudder which occurs with new friction materials before break-in. To do this, an ATF is used in which the friction modifier system consists essentially of (i) an N-aliphatic hydrocarbyl-substituted diethanolamine in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of 14 to 20 carbon atoms, and (ii) an N-aliphatic hydrocarbyl-substituted trimethylenediamine in which the N-aliphatic hydrocarbyl-substituent is at least one straight chain aliphatic hydrocarbyl group free of acetylenic unsaturation and having in the range of about 14 to about 20 carbon atoms. The ATF is devoid of any tertiary amine friction modifier component and any C.sub.12-36 aliphatic hydrocarbyl succinimide or succinamide friction modifier. Specified relative proportions and concentrations of (i) to (ii) are used.

Automatic transmission fluids and additives therefor

A new friction modifier system is described. It has the capability of establishing and maintaining a substantially constant static breakaway coefficient of friction between a pair of friction surfaces that are periodically frictionally engaged with each other. Also this system is capable of maintaining a substantially constant ratio between (i) the low speed dynamic coefficient of friction of such friction surfaces, and (ii) the (midpoint) dynamic coefficient of friction of such friction surfaces. The additive composition yielding these results comprises at least the following components: a) a hydroxyalkyl aliphatic imidazoline in which the hydroxyalkyl group contains from 2 to about 4 carbon atoms, and in which the aliphatic group is an acyclic hydrocarbyl group containing from about 10 to about 25 carbon atoms; and b) a di(hydroxyalkyl) aliphatic tertiary amine in which the hydroxyalkyl groups, being the same or different, each contain from 2 to about 4 carbon atoms, and in which the aliphatic group is an acyclic hydrocarbyl group containing from about 10 to about 25 carbon atoms.

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Brentwood, MO, United States of America

Hiroko Ohtani