The readers will be turned off for the afternoon peak from Thursday, after members of the Rail, Tram and Bus Union voted in favour of taking protected industrial action last week.
From 3pm to 7pm every weekday - for an indefinite period - the readers will be switched off, RTBU secretary Alex Claassens told media on Monday.
The union is hoping to create a major headache for the government, while keeping commuters on side with the move.
A possible issue has emerged, however, that some commuters may be overcharged if unable to tap off once machines are shut down at 3pm.
Commuters who do not tap off are charged a maximum fee, which can be as high as the daily cap of $16.80 for an adult.
Those commuters will have to contact Transport for NSW where they then have their fare adjusted, Craig Turner from the RTBU said.
It's expected the NSW government will launch a Federal Court challenge to the industrial action, although the government let expire an earlier opportunity to oppose the action within the Fair Work Commission.
The move is the latest in an extended and bitter dispute between the government and the rail union, as the parties try to negotiate a new enterprise agreement after the previous one expired.
They are also at loggerheads over a mothballed fleet of Korean-built intercity trains, which the union says are unsafe to operate.
After weeks of private conciliation meetings between the two parties, little had been achieved, Mr Claassens said.
"We did get some movement on a couple of items but as always, the government refused to send a decision maker to the table," he said.
"Everybody is fed up with the ongoing rail dispute, but we've no choice but to continue to do whatever it takes for as long as it takes to force the NSW government to provide safe trains for commuters and fair wages and conditions for workers."
Shutting down the gates around-the-clock was estimated to cost the government between $1.5 million and $2 million in lost revenue each day.
It would cost the government approximately $50m if the shutdown continued for a month.
Earlier this year the union also tried to hit the government in the hip pocket by leaving ticket gates open.
That was largely unsuccessful, with most commuters continuing to tap on and pay for fares.
Premier Dominic Perrottet last month said people were not interested in the union's tactics and just wanted to get on with their day.
"The reason (the union) have moved to shut down the machines is because by leaving the gates open, the majority of people in our city tapped on and tapped off," he said.
Treasurer Matt Kean last month accused the union of using the travelling public as political playthings.
"It's got to stop," he said.
"We will continue to stand up for the people of this state and call out their disgraceful behaviour."
AAP has contacted the NSW transport minister and Transport for NSW for comment.
