When the US Golf Association announced last Wednesday that it will continue to study advances in club and ball design and construction before imposing new - and much feared - restrictions, golf equipment manufacturers proclaimed themselves relieved and pleased.

For now.In recent weeks, major equipment makers in the $2.5 billion industry, including Titleist and Spalding in Massachusetts, had mounted a public relations offensive. They feared that the USGA, the governing body of professional and recreational golf, was poised to adopt Draconian restrictions that would even ban clubs currently used on the professional tours and at the local country club.

"They are taking a more conservative and rational approach and they've done a good job of listening to the manufacturers and the consumers," said Scott Kreelman, executive vice president of Spalding.

The manufacturers feared that the USGA would use the eve of the US Open in San Francisco to announce new rules that would ban several new clubs and sharply curtail future research and design.

The issue of new technologies and the impact on the game is being played out amid enormous stakes for the manufacturers and the USGA alike.

Manufacturers of clubs earned $1.7 billion in wholesale business in 1997, an increase of 74 percent in just four years, according to the National Golf Foundation, an industry-supported research group. Manufacturers of golf balls made $667 million in wholesale business last year, an increase of 23 percent from 1993.

New USGA rules would strike at the heart of the industry, which relies heavily on major advancements in technology to market new products every few years. But when top USGA officials took the microphones at The Olympic Club golf course in San Francisco last week, they were anything but confrontational.

"We are not uncomfortable with what we see on the market today," said David Fay, USGA executive director. "We don't believe that clubs submitted at this point have lessened the skill to play the game at championships such as the US Open or at a recreational level."

Fay and other USGA officials outlined a plan to establish a formula to measure the "spring-like effect" that occurs when a club face hits a ball. What the officials, and many golfers, are concerned about is that new technology may be artificially putting more power into shots.

The formula for determining the maximum allowable effect will be sent to manufacturers in a proposed protocol within the next few weeks, Fay said. The companies will then be allowed the rest of the summer to comment on the proposal, before meeting formally with the USGA to discuss the issue further in the fall.

Fay also said that the USGA continues to examine golf balls in an attempt to determine an acceptable level of design advancements. He said no restrictions are currently contemplated.

Some manufacturers, though, remain concerned that the USGA may eventually seek to halt the enormous strides in technology that have made clubs lighter, more accurate, and capable of striking a ball farther.

"The USGA still feels it needs to protect the game from equipment manufacturers, and I strongly disagree with that," said Donald Dye, chief executive of Callaway Golf Co., the Carlsbad, Calif., manufacturer that has led the way in club designs. "But, at least now, consumers will feel comfortable buying what we have in the market."

The USGA's concern is that younger, stronger players, combined with space-age technology and materials, will overwhelm courses. The association has already turned down a bid by the Merion Golf Club outside of Philadelphia to host its fifth U.S. Open because the course is not long enough. Perhaps most alarmingly, the famed Old Course at St. Andrews in Scotland is planning to lengthen its layout, a massive bit of construction and landscaping that some in the sport consider to be sacrilegious.

And, on June 9, the Augusta National course, which annually hosts the Masters tournament, announced plans to lengthen a few holes and to add trees to counter the game's big hitters. Just a year ago, Augusta said it would never consider such changes.

The average drive on the PGA Tour has increased from 260 yards to 269 yards in five years. In that time, several companies have introduced clubs and balls, each promising to deliver easier, longer, more accurate play. Perhaps the major factor in the increase of sales of clubs is this repeated introduction of new technologies.

Titleist, a division of Fortune Brands in Fairhaven, and Spalding, in Chicopee, control 70 percent of the market in golf balls. Both companies have been fighting a continual war for market share.

Much of the battle is waged in company laboratories, where as many as 50 research and design workers compete. New balls with new promises of longer, more accurate flight are introduced virtually every other year.

"All of the companies are highly motivated by the bottom line in terms of what they make and whatever advancements they can get out on the market."