There is something about a Hostess Twinkie that dissolves the walls between men. So it went between Thomas Jones and Richard Nixon.

"I had forgotten my Twinkies, so I went back to the truck and got a whole double armful," said Jones. "Then I got to the door, but I ran out of hands. I couldn't open it."

At just that moment, Richard Nixon appeared. His three Secret Service bodyguards tried to hustle Jones out of the way. But Nixon always did have an independent streak.

"I couldn't believe it. He held the door for me, insisted on it. Yeah, it kind of embarrassed me, but here, you get used to it."

"Here" is the White House, and Tom Jones has spent much of the last 12 years keeping it human in a special way. He is the man who fills and tends the White House vending machines. The guy who keeps the presidential machine-food addicts happy.

Tom Jones has seen the Johnson daughters, quarters in their fists, waiting to assault an East Wing ice cream machine he was filing.

He has overhead David and Julie Eisonhower argue the respective merits of Powerhouse and Chuckles candies.

He once stood by as Attorney General Griffin B. Bell fed a dollar bill into a change machine. Out came nothing. Out of Bell's mouth came a stream of words he never learned in law school.

Tom Jones once came within an inch of running over Walter Mondale's foot with a hand truck. He once watched the entire Cabinet trying to retrieve a quarter from a balky soup machine. He was once asked by Nixon staffer Stephen Bull to stock a certain kind of cookie - and refused, because the cookie was a poor seller.

The ultimate in Jonesian independence came just after Jimmy Carter arrived. Jones decided not to stock peanuts in the White House machines. "I was sick of the jokes, man," he explained.

The peanuts are now back, by popular demand, "but to tell you the truth, the Johnson and Nixon people bought twice as many of them," Jones said.

Tom Jones' White House route begins every weekday at the stroke of 5 a.m. when he pulls Truck 84 away from the Macke Company loading dock in Cheverly. Twenty minutes later, he is at the east gate, where he balances three baskets of food on his knee, hands a policeman his pass and says the magic words: "Thomas Jones, date of birth 4-10-46."

The guards all know Jonesia, of course, so the careful scrutiny they give his baskets is more a matter of personal interest than of national security. Other than from a Macke machine, the White House police have nowhere to buy a meal. So when Jonesie turns up with a favored kind of sandwich, the smiles on police faces are genuine.

Past Grover Cleveland's portrait, down a freight elevator, and Jones is in the East Wing basement. Most of Macke's machines there are in the police squad room, and Jonesie's visit comes just before the shifts change, so there is usually a sizable audience bugging him to hurry up and fill the coffee machine.

He was doing just that one recent Thursday morning when, at the stroke of 558 and without warning, bells started clanging. A newcomer might have thought it was an air raid, but White House veteran that he is, Jones never even looked up. "Guess he's in," he mumbled.

In? What? In where? Who's in?

"The President,t said Jones. "He just walked into the Oval Office." As many times as he has heard the clanging for four early-rising Presidents, "Yeah, I still get a kick out of it."

He also gets an obvious kick out of the gang that usually awaits his arrival in the West Wing basement machine room.

The shifts are changing there, too, so a dozen carpenters, electricians and plumbers are on hand to greet Jones. The men call themselves The Kitchen Cabinet. They argue about football, politics, women, whatever, and they claim they can solve any problem in one-tenth the time The Big Boss takes.

The reason,they claim, with hoots of laughter, is that Jonesie's food is brain food. "You can tell it when he takes a week off," said one electrician. "The food isn't as fresh, and neither is the conversation.

Jones has nine machines to fill in this room, and as one Kitchen Cabinet member put it, "Jonesie humps."

Not only does he refill the machines. Not only does he remove all the money. Not only does he have to examine each sandwich to make sure it hasn't been there for more than two days. But this day, the quarter-changer is giving back 20 cents.

"This is the one place you don't want this to happen," said Jones. Opening the machine with one of his four dozen keys, he quickly discovers the problem: oil and grease in the trough. "First guy gets 20 cents, next guy gets 30," Jones says. A good rubdown with a cloth, and things are normal again.

Jones has had many other frustrations as the White House Macke Man.

All vending machines will stop working if a Canadian coin is used. But at the White House, "I'm more likely to get an argument about how a Canadian quarter is worth more than our quarter."

Tom Jones has three other downtown stops after the White House, but like so many men who have spent time there, it is 1600 Pennsylvania Avenue that sticks in his mind.

"It's really been an experience," said Jones. "You see and hear a lot of things. I'm really proud of the fact that I have that stop. You get a different angle on things."

Jones guns his truck along New York Avenue. "Like take Nixon. If all you did was read the papers, you'd think Watergate was all Nixon was. But, hey, I know he held the door for me that time."