London Underground bosses last week threatened to dock workers’ pay for taking part in industrial action.
The RMT and Aslef unions have instructed drivers not to operate trains unless they have been “subject to safety checks” in the previous 24 hours.
But bosses sent a letter to drivers, which threatened not to pay workers for their whole shift if they refuse to take a train out.
Management said it would also impose normal shift patterns on the 31 August bank holiday because of RMT members’ overtime ban.
The ban is part of an ongoing battle against bosses’ plans to change terms and conditions and attack pay when the Night Tube begins in September.
Bosses want to impose new rosters on the Night Tube, which would force workers into unlimited night and weekend shifts.
All four Tube unions plan to strike for 24 hours on 5 August against these attacks. This would be the second walkout by the RMT, Aslef, TSSA and Unite union members.
There is also a possibility that London bus workers in the Unite union could walk out alongside Tube workers.
Tube workers united walkout in early July saw a total shutdown of the network—it showed workers’ power to take on the bosses.