Mutuel clerks at Aqueduct reached a tentative contract agreement with the New York Racing Association on Thursday, bringing near an end a seven-week strike marked by violence and vandalism.

But the end of this strike represents only the beginning of an era of labor trouble at the nation's racetracks. This is inevitable, because the introduction of labor-saving technology into an industry is almost always accompanied by bitter clashed between unions and management. And now the process of selling tickets at a racetrack, virtually unchanged for the last four decades, is undergoing a revolution.

The cause of this revolution is the American Totalisator Co's TM 300 system, a computerized ticket-selling process that was introduced to thoroughbred racing at Gulfstream Park this winter. After using the machines there, and then coming back to the traditional equipment at Pimlico, I feel as if I am driving a horse and buggy in the space age.

At Gulfstream, every window provided every possible parimutuel function. A customer could buy and cash tickets of every type and amount, whether $2 exacta tickets or $250 win tickets.

The machines eliminated many cumbersome manual functions-such as the cashier's laborious pencil-and-paper calculations of the payoff from a stack of winning tickets. Now he merely slides the winning ticket through a slot, and the amount of the payoff instantly flashes on the face of the machine.

the greatest virtue of the new system is its ability to handle the gimmick bets that have become so popular at American racetracks. The traditional tote machine, introduced in the 1930s, were adequate to handle the win-place-show wagering of that era, but proved hopelessly cumbersome when used for exactas and triples.

A horseplayer at Pimlico who wants to play No. 2 to win in the triple, with Nos. 3, 5, 6, 7 and 9 second and third, investing $10 on each combination, will spend at least five minutes at the window while the seller punches out 100 tickets.

At Gulfstream a customer could make the same wager simply by saying, "Ten dollar key box, two-three-five-seven-eight-nine," and the entire wager would be recorded on a single ticket.

Obviously, the fact that a mutuel clerk might have to punch out one ticket instead of a hundred on a certain transaction means that racetracks will need fewer mutuel employes. And there are other aspects of the new technology which further disturb the unions. The TM 300 destroys the old hierarchy of the mutuel clerks, which gives employes with seniority the jobs at higher-denomination windows which pay higher salaries. Now everybody performs the same functions, and earns the same pay.

Operating the new machines requires intelligence and specialized training. Judging from Gulfstream's experience, some clerks will have trouble learning the new technology. And they will be likely to commit costly errors, for which they can be held personally accountable.

All these concerns underlay the New York strike, and explain why men being overpaid at $28,000 a year would be moved to set off bombs and vandalize cars in the parking lot.

Fears of the new technology already are causing problems elsewhere.

At Keeneland, where the TM 300 system was introduced yesterday, clerks were working only because a federal judge ordered them to submit their contract dispute to arbitration.

At Hollywood Park, which plans to introduce te new machines next week, the union has stated flatly that it will accept no automation. So the track is training 1,000 strikebreakers to replace them.

Such battles probably will continue for years. But when they have subsided, and the TM 300 equipment is standard, racetrackers will wonder how they ever lived without computerized betting.