The SYSTEMA PTW gearbox is very unique and innovative. Many wonder how the SYSTEMA PTW works and how the new gearbox type looks like. So we have made a closeup on this planetary gearbox to show how it is made. This will provide you some details and insights on this great piece of mechanics. This is the way SYSTEMA puts it:
"Revolutionary implementation of the planetary gear box allowing the weapon to operate smoothly and reliably under high internal stress, while reducing the overall package dimension.
Compared with the conventional reduction mechanism with three shafts, the planetary gear has only two shafts, allowing for a more compact mechanism. The planetary gear, which originally had three gears, was redesigned to have four in order to provide higher durability for the thrust load when using a high-rate spring.
Due to this effort, we succeeded in reducing to the greatest possible limit the backlash caused by the gears biting each other, resulting in realizing the best in transmission efficiency."
When opened you are able to see how compact and small everything is. This is the MAX gearbox from the PTW challange kit also named "do it yourself kit". This gearbox is practical the same to all PTW gearboxes out there. In total the gearbox includes 28 parts! Please find more information in the exploded views we included at the end of the review. This particular MAX gearbox is made to withstand a 160m/s spring and almost NO maintenence needed. Many new to SYSTEMA PTW ruin their gearbox by adding grease/lubricate because it looks dry. The problem is that the gears are so tight made together that thick lubricate would blow the gears or make it very hard to turn and blow the fuse/melt curcuitboards. So no further lubrication is needed, please be carefull with that!
Taking a closer look on the gears you would notice that this is really nothing like a regular Ver2 AEG gearbox.
When looking from this angle I would try to explain the operation of the gearbox. To the left you got the curcuitboard EL-001 and got a switch for the trigger. It also got a photoswitch that check the position of the main gear so it would always return to normal position. The two holes in the main gear is for the photoswitch to see trough. Top left you got a white switch that is connected to the bolt catch. When the magazine is empty it press out the bolt catch and stop firing. When inserting a new full magazine you have to tell the electronics to restart so you could fire again and do this by pressing in the bolt catch that again press the switch. BTW!!.. The KUMI stamped in the gearbox is the name of the CEO in SYSTEMA :) Further not of any importance...
On this side you can see the electronic controle of the semi/auto/burst with the selector switch. The EL-002 got two microswitches. When the selector is set to safe the selector arm is to the right with no contact to the switches. When set to semi it press down the first switch and tell the electronic to fire one and one bb. On auto/burst the arm press down both switches and telll the circuit to do auto or burst after what type of EL-001 you got. If you want to lock to semi only you could either restrict the arm only to go to the first switch or you could remove the cable to switch two.
On top of the gearbox is a hole where the firmnes of the selector is adjusted. First there is a bearing ball laying on the selector switch. the selector switch got 3 dents on it where the ball would press down in for each selected Safe/Semi/Auto. You adjust how hard the selector should feel by adjusting the screw on to the spring that press down the ball. A nice function to set the firmnes of the selector to your own preferences!
Download here the PDF document with exploded drawings of the gearbox. You will find part information also...