After complaining that a vote Thursday on a bill to require trucks to cover their loads had been unfair, proponents of the measure failed today to muster enough support to bring the bill to a second vote.

The bill, which had been approved by the Maryland Senate, was under consideration in the House Enviromental Matters Committee and needed approval there before it could be voted on by the full House. But wile 10 of the committee members were absent Thursday, Chairman Torrey C. Brown (D-Baltimore), called for a vote on the bill.

At least eight of the members who were out of the room supported the covered truck measure and today 14 members voted to have the bill reconsidered. But an unwritten committee rule requires that a bill get 18 votes-a three-fourths majority-to be reconsidred, and thus the bill went down again to defeat.

An angry Sen. Howard A, Denis (R-Montgomery), the latest in a long line of senators to sponsor covered trucks legislation, termed the handling of his bill in the Environmental Matters Committee, "a mockery of legislative process."

"It's an example of how a powerful [trucking] lobby which contributes heavily to campaigns can prevent good legislation from getting to the floor [for a vote] even when a majority of committee members are for it."

The vote to reconsider the bill was 14 to 9 in favor. Denis took the vote as evidence that the bill would have passed the committee on Thursday if more members had been present.

Supporters of the bill, though disappointed that they could not muster the necessary 18 votes, said they would not petition the full House to vote on the bill, saying that would only alienate the House leadership.

Rules determining whether bills that have been defeated in committee can have a second chance vary. The House Judiciary Committee, for example, will not take a second vote on any bill. Other committees require a simple majority to support a motion to reconsider a piece of legislation.

When the first vote was taken Thursday, several committee members were out to lunch. Two years ago, the bill was killed under the same circumstances, according to Sen. Frank Shore, who was then a delegate on the committee and a supporter of the bill.

"We were done in by our own rule [on reconsideration]," said Del. Kay Bienen at today's vote. "The damn bill hasn't passed for 10 years, but maybe ti will pass next year."

The delegates who voted for reconsideration were: Kay Bienen (D-Prince George's); Anthony Cicoria (D-Prince George's); Thomas W. Chamberlain Sr. (R-Baltimore County); Anthony M. DiPietro Jr. (D-Baltimore); Raymond Dypski (D-Baltimore); Marilyn Goldwater (D-Montgomery); Sheila Hixson (D-Montgomery); Paula Hollinger (D-Baltimore County); Thomas Mooney (D-Prince George's); Joan Pitkin (D-Prince George's); Steven Sklar (D-Baltimore); Judith Toth (D-Montgomery); Gerald Wine-grad (D-Anne Arundel); and Larry Young, (D-Baltimore).

Delegates who voted against the measure included Irwin Hoffman (D-Washington); Hugh Burgess (D-Howard); Roy Dyson (D-St. Mary's); James McClellan (D-Fredrick); Daniel Minnick Jr. (D-Baltimore County); Catherine Rilley (D-Harford); Lewis R. Riley (R-Wicomico); W. Henry Thomas (D-Dorchester); Michael H. Weir (D-Baltimore County).

Chairman Brown did not vote.