They are armed with wrenches instead of rifles and are rarely found on the front lines, but Mosul`s mechanics say they are indispensable to the fight against the Islamic State group.
"If the Humvees break down and the weapons stop working without anyone to repair them, how could we advance against IS?" says Lieutenant Colonel Anwar Rajdi, who heads the mechanics unit of the elite Iraqi Counter-Terrorism Service (CTS).
The tall commander proudly says his unit is "the most important part" of the month-long fight for Iraq`s second city, the last one in the country still held by IS.
As they advance farther into the city`s easy, CTS forces are facing a daily barrage of sniper fire, mortar attacks, and car bombs from the jihadists who still hold much of Mosul.
Between 15 and 20 damaged Humvee armoured vehicles are brought to the repair unit on the edge of the city each day, dragged by massive white tow trucks, CTS mechanic Mustafa Muin says.
Most have had their windows cracked into a spiderweb of glass by repeated shots from IS sniper rifles, and some need a quick tune-up for their radiators or engines.
Others need their tyres changed after driving over the long metal spikes IS fighters place in Mosul`s narrow alleyways to slow down advancing units.
An infographic distributed by the jihadist-linked Amaq news agency on Tuesday said that IS destroyed nearly 50 Humvees and four tanks during the battle for Mosul.
"Fixing the radiator takes us half an hour, but an engine takes us half a day," says Muin. He is overseeing two grease-covered colleagues struggling to dislodge a damaged radiator.
"We try to get the machines back up and running so we can finish work by nighttime and relax," he tells AFP.
On days where fighting is intense, technicians are dispatched to the front lines to do on-site repairs.
They crawl under damaged vehicles to swap out parts, their feet sticking out dangerously while bullets ping off nearby houses.
But when CTS units are reinforcing their forward positions, the pace is more relaxed with repairmen passing the time pumping iron in a shaded courtyard.
"We repair about 20 weapons per day if there`s an advance, but if there`s no advance, you can clearly see I don`t have much work," says Atheel Shaalan, who is responsible for servicing arms including "all types of American weapons."
American-made equipment that Iraqi special operations forces use include assault rifles and armoured vehicles.
Large vehicle parts, such as engines and radiators, are regularly trucked up from Baghdad to the edge of Mosul.
Mechanics also try to salvage whatever parts they can from the charred remains of vehicles that were damaged beyond repair by IS car bombs.
"We`re helping the fight against Daesh back here at the factory," says mechanic Qusay Adnan, using an Arabic acronym for IS.
"I`m not a soldier fighting on the front lines, but I`m just like them."