The 9-to-5 straitjacket is on the way out for many Americans as increasing numbers of employers learn that permitting workers some leeway in setting work schedules may bring an end to a host of other management headaches.

Flexitime, or gleizeit, which in German means glide time, was developed in Munich in 1967 at the Messerschmidt Belkow Co. The concept has spread faster than any othe management innovation in recent years.

U.S. Civil Service figures reveal that 50 per cent of the West German white collar work force has some say in the arrangement of its working hours, while 30 per cent of the French labor force and 40 per cent of all Swiss workers are now on some form of flexitime. The British government recently approved variable hours for a half million civil servants. Surveys estimate that more than 9 million workers in 10 countries have some control over their jobs hours.

Flexible scheduling seems to inspire renewed job interest among employees because it allows for career development as well as more time for community, family educational and recreational functions. It may benefit women, especially those with children, more than men.

Management gains frequently cited are lower rates of absenteeism, tardines and use of personal days, as well as improved customer relations - all won without increased costs. Some firms find that they can remain open for more hours a day without increasing the payroll. Most employers find that the concept attracts higher-quality workers.

Since its introduction in the United States about 5 years ago, the variable-hour plan has been embraced enthusiastically embraced by a small but signigicant sector of American industry.

A company representative of the First Natioanl Bank of Baltimore, which is on flex, declared, "Our people like the system. Tardiness has virtually been eliminated, fewer workers are absent, turnover is down, and productivity and morale have risen."

"The Nestle Co. of White Plains, N.Y., recently gave its white collar workers a choice - 700 opted for the plan. In Minneapolis, Rosemount(a producer of aerospace instruments) has 800 workers on variable scheduling. The company reports that the workers prefer it to the 4-day week which had been used earlier.

The California electronics firm, Hewlett Packard, is the U.S. company by far the most reliant on flexitime - 22,000 of its employees enjoy variable hours.

Some firms have been reluctant to adopt flexitime without further study. The Mine Safety Appliance Co. of Pittsburgh agreed to inaugurate the plan on a strict trial basis in June 1974. After some rigid testing, the company found that production actually increased when time clocks were eliminated and flexitime was substituted. By early 1975, it was made a permanent scheme for the company.

Experts who study flexitime find that it benefits individuals' personal lives and contributes to the community. Jerome Rosow, president of the non-profit Work in America Institute of Scarsdale, N.Y., observes that flexitime strengthens family life.

"It gives workers greater freedom to choose their lifestyles without adverse effects on production," he said. He added that the plan would be of substantial community benefit during an energy crisis because it disperses people in large urban areas and breaks down rush-hour congestion.

In Connecticut, the Department of Environmental Protection suggested to industry that flexitime is one of the least costly and easiest to implement methods of complying with the federal Clean Air Act because it encourages car pooling and allows for a 4-day week.

President Carter recently advocated that flexitime be tried in some government agencies, and the U.S. Civil Service Commission already is experimenting with it. The House of Representatives has passed legislation permitting a 3-year test of flexitime in other federal agencies as well.

The Work in America Institute, which assists companies in setting up flexitime plans, estimates that about one-third of a million Americans choose their own flex hours and that many more will be added in 1977.

It cites the plan used by the Berol Co. of Danbury, Conn., as one of the best in the nation. Berol, a multinational giant, produces Eagle brand pens and pencils. In the summer of 1973, it started its plan.

The work schedule from September to May involves 40 hours over 5 days. Twenty-five hours of core time is prescribed from 9:30 a.m. to noon and 1:30 to 4 p.m. each day. The remaining 15 hours are flexed according to workers' wishes after clearance from department heads.

During June, July and August, those workers who complete their 40 hours by noon Friday are excluded from the afternoon's core requirement.

Berol reports a 50 per cent decline in absenteeism, a drop in lateness from 5 per cent to 1 per cent, a drop in average personal leave days from 2.3 to 0.2 per year, along with improved morale, decreased traffic congestion and, most importantly, no decline in productivity. Benefits have been so significant that Berol plans to implement the plan corporation-wide.