Keith Emerson seems to think he's Arthur Rubinstein, or at least Keith Jarrett. Greg Lake apparently has his heart set on becoming another Stephen Sodheim. And Carl Palmer acts as if he were auditioning for Saul Goodman's percussion chair in the New York Philharmonic Orchestra.

Those are the three main reasons there's not much that's identifiable as rock 'n' roll on "Works, Volume 1" (Atlantic SD 2-700), Emerson, Lake & Plamer's first album in nearly three years. With this portentously titled double set, rock's only classically oriented power trio, whose past credits include pop versions of works by Mussorgsky, Ginastera and Copland, have taken their search for respectability to new lengths - losing, in the process, what pop credentials they still had.

You can tell that you're in for a heavy dose of seriousness on "Works" just by glancing at the album's elaborate but severe black-and-white cover package, which lists Lake not as a singer, but as supplying "vocal interpretations." That kind of pretentiousness turns up repeatedly throughout "Works," which is divided up in such a way that each member of ELP gets one side to himself before reuniting with the other two for the group grand finale on side four.

Emerson starts things off with his Piano Concerto No. 1, and ambitious and dramatic 17-minute composition in three movements: allegro giojoso, and ante molto cantabile and toccata con fuoco. Recording with the London Philharmonic Orchestra, Emerson holds his own as a pianist, displaying impressive technique during several solo passages, but never gets around to resolving certain basic weaknesses in the score itself.

Emerson's biggest problem as a composer is that though he is quite capable of scoring for brass, his string writing tends to be both clumsy and overblown. Unlike jazz, pianist Keith Jarrett, whose "In The Light" and "Arbor Zena" are perhaps the finest recent examples of orchestral music composed by a non-classical musician, Emerson lacks both restraint and imagination.

Bassist, guitarist and singer Lake, who contributes "C'est La Vie" and "Closer To Believing," a pair of pseudo-show tunes, to the album, is a bit less bombastic. But when he and lyricist Pete Sinfield, writing partners since the early days of King Crimson, team up with Emerson and his synthesizer on "Pirates, " the murky, 13-minute, made-for-Broadway opus that ends the album, things get completely out of hand.

Oddly enough, it's percussionist Palmer, performing on the instrument that pop musicians most frequently overplay, who emerges as the most tasteful member of the trio. True, his rendering of Prokofiev's "Scythian Suite" has its moments of excess, but his arrangement of Bach's Two Part Invention in D Minor is a delight - he fleshes out a simple string part with tuned drums, tubular bells, vibes and mirimbas.

Two more contemporary pieces also show Palmer in top form: The jazzy "Food For Your Soul," which might be subtitled "Buddy Rich meets the Tonight Show Orchestra," and a rock trio with orchestra version of Aaron Copland's "Fanfare for the Common Man" in which has splendid work on tympani is eventually overpowered by Emerson's flashy forays on the brand-new Yamaha GX-1 synthesizer.

Listening to Emerson barrel his way through "Fanfare," using his expensive new synthesizer as if it were merely a "switched-on" version of an organ, is an annoying but enlightening experience. Though Emerson early acquired a reputation as a "keyboard wizard," it's obvious from his work on "Works" that he has now been surpassed by Jan Hammer, Tangerine Dream's Edgard Froese and several other less-celebrated synthesizer players.

The Emerson, Lake & Palmer approach seems out of date, if not insulting, in another respect. Most of rock 'n' roll musicians - and listeners - have long since outgrown the notion that it takes the imprimatur of a classical father-figure like Leonard Bernstein to make their music legitimate. ELP has never gone beyond that stage, and "Works, Volume 1," makes it even more doubtful that they ever will.