Crew Replenishment is a module available for ground vehicles.
Crew Replenishment Official Description
In Arcade mode, you can request a draft at any point on the map, and if there is only one tanker left in the tank, the draft is requested automatically and all you have to do is hope that the soldier arrives in time. It’s all quite simple, the only thing you have to consider is that the vehicle cannot move between your request for a crew member and the time the crew member arrives.
It’s a little more complicated in Realistic and Simulated modes. Here, you can only draft a tanker at a safe capture point that belongs to your team, and you can only draft a crew member manually. This is in contrast to Arcade mode, only a battle-capable vehicle with a minimum of two living crew members can draft a new crew member. It will also be impossible to move while the replacement is being fulfilled.
Crew drafting will become available after you research the ground vehicle modification of the same name. Each individual replacement tanker draft costs Silver Lions.
Ground vehicle's survival is mostly based on the crew inside the tank. If only 1 crew member is left remaining or is killed as well, the tank is considered "knocked out". Gaijin had added a few different mechanics in an attempt to increase ground vehicle's survivability
The first attempt happened in 15 March 2016 in Update 1.57 with the mechanic known as Last Man Standing. This effect only works in RB and SB gameplay and basically makes the last crew member in the tank a viable fighter, able to transition between driver and gunner position until he himself is also knocked out. Another mechanic that Gaijin announced was the Crew Medkit on March 24, although its implementation is not seen or reported in-game. However, Last Man Standing proved controversial in the player base. The mechanic gave tanks with larger crew count a very large advantage when down to just a single crew member, effectively allowing the player to consistently switch the positions of their last crew member and forcing the shooter to play a "whack-a-mole" with the last crew member. Along with complications with the implementation of the mechanic in said large tanks as well, Last Man Standing was removed from the game in May 11th as Gaijin finds another solution.
The second attempt at this problem was in June 2nd with the Crew Trauma packs. Similar to the Crew Medkit mentioned since March, the Crew Trauma packs work similarly by allowing the player to patch up one of their fallen crew members in battle (whether it was simply one person or the whole crew was not stated). It is also automatically used if the tank crew falls to just a single survivor. The mechanic was to be implemented in Update 1.59 "Flaming Arrows", but criticism from the player base caused Gaijin to send this mechanic back to the drawing board.
In the development period before Update 1.61 "Roads to glory", Gaijin announced their new module Crew Replenishment on July 27. Unlike the other mechanisms which heals one of the existing crew members in your tank, Crew Replenishment does the action of "drafting" a tanker outside to arrive and take a crew member place in the tank. The module works on AB, RB, and SB modes with slight differences. In AB, the module can be used anytime a crew member is knocked out and also if the crew count goes all the way to one, but will be nullified if every one in the tank is killed at once. In RB and SB modes, the module only works on a safe captured point and will not automatically call one in during battle if all but one of your crew members are killed. In all modes, the reinforcements takes time and the player cannot move while it is in use.
Currently, Crew Replenishment is still in the game.