J. Bernard West, 70, a discreet, self-effacing and efficient Iowan who had the extraordinary job of chief usher of the White House and served under six presidents, died of respiratory failure July 18 at Northern Virginia Doctors Hospital. He had undergone surgery for a lung ailment.

Mr. West began his career in the Executive Mansion on March 1, 1941, as an assistant to Howell G. Crim, then the chief usher. In 1957, when Crim retired, Mr. West succeeded him. He himself retired in 1969, having worked for the Franklin D. Roosevelts, the Trumans, the Eisenhowers, the Kennedys, the Johnsons and the Nixons.

"What does the chief usher do?" he was sometimes asked. "I do what I'm told to do," he would say.

Of course, he did do what he was told. But there was more to it than that, just as there is more to the job of being chief usher at the White House than the term implies. The first chief usher was Irwin H. (Ike) Hoover, who served from 1891 to 1933. His principal duties included making up the president's appointment calendar and ushering distinguished visitors into his presence.

By the time Mr. West went to work, that had changed. The chief usher became the man responsible for running the White House: making its occupants comfortable, caring for guests, arranging dinners, arranging for flowers, fixing the plumbing and the roof and the air conditioning, organizing and justifying the budget, arranging for the 2 million tourists who visit it each year, safeguarding the treasures that decorate it, supervising everything that has to do with making it a residence, a national monument and an office.

Most of all, of course, he is responsible for making the First Family comfortable and in this endeavor he works closely with the First Lady.

A man who holds such a position has many a tale he could tell. But in all his years at the Executive Mansion, Mr. West refused to be interviewed. In fact, when John F. Kennedy moved into 1600 Pennsylvania Ave. on Jan. 20, 1961, Mr. West suggested that members of the domestic staff, who number more than 100, sign pledges that they would not exploit what they heard or saw for profit.

But in 1973, he wrote the best-selling "Upstairs at the White House" with Mary Lynn Kotz. Rather than "telling all," the book gives a charming and informative picture of life with six different families.

From Mr. West, we learn that the Roosevelts lived separate but more or less equal lives. Mrs. Roosevelt would go horseback riding alone in Rock Creek Park and had a way of inviting luncheon guests at the last minute. Butlers bearing brandy to Winston Churchill would find the great statesman in the buff in his bedroom.

The Trumans were a close and homey family and hardly seemed troubled at all when the Corps of Engineers discovered that the building was literally on the point of collapsing and that they would have to move across Lafayette Square to Blair House while a major renovation was undertaken.

The Eisenhowers, beneficiaries of that renovation, seemed prepared to make do with it or without it, as military families always make do. The Kennedys brought with them the cosmopolitan style of the New Frontier. The Johnsons were different yet again. President Johnson ordered the installation of special shower heads that seemed to generate the force of a fire hose. President Nixon had them removed.

The secret to Mr. West's success in his job and with his book may reside in these sentences, which appear in his foreward:

"My loyalty was not to any one President, but rather, to the Presidency, and to the institution that is the White House . . . I came to know and admire Eleanor Roosevelt, Bess Truman, Mamie Eisenhower, Jacqueline Kennedy, Lady Bird Johnson, and, briefly, Pat Nixon. Each brought with her a different viewpoint, a different life style, and each, in her own way, using her own background and training, made a special imprint upon the President's House, and her own contribution to the heritage of the United States."

Mr. West, who was called "J.B." by his friends, was born in Afton, Iowa. He moved to Washington in 1939 and went to work as a clerk in the Veterans Administration. Crim, his predecessor, hired him away from that job. During World War II, he served in the Navy and was immediately detailed to continue his work at the White House.

Following his retirement, Mr. West, who lived in Falls Church, organized an association for retired members of the Executive Mansion staff.

Mr. West's survivors include his wife, Zella, of Falls Church; two daughters, Sally West of San Francisco, and Kathy Langhoff of Anchorage; two sisters, Irene West of Washington, and Genevieve Fleming of Creston, Iowa, and two grandchildren.