This page is for the more advanced technical specifications on the operation of Nerves.
Design Definitions:
Simply put, this is how the marker operates. When firing, the ram is pushed forward by air pressure from the solenoid. Once it reaches the forward position the front of the ram pushes open the delrin valve poppet and allows air stored in the marker body to be released up and through the bolt. The movement of the bolt is linked to the movement of the ram since they are physically connected, so once the valve opens the bolt is already in the forward position, and is used to shunt pressure through the chamber and down the barrel.
This type of marker is generally referred to as an open bolt electropneumatic design, more specifically a stacked-tube open bolt electropneumatic. This is because the bolt is contained in the upper bore whereas the firing components are in the lower. This design has been around nearly since the beginning of paintball markers (in a more basic, mechanical form), and similar concepts can be found in many other markers as well. These include the Angel, Impulse, Intimidator, Bushmaster, Tribal, Viking, NME, Wrath, Promaster, Ego, Diamdem, and others.
The advantages to this type of design are high cycle rates, and secondly the combination for many different balances of settings and pressures. Hammer/valve markers are able to translate relatively small mechanical kinetic energy into higher amounts of force to make them fire. This allows for high efficiency with low cycling times if properly set.
Firing Assembly Synopsis: 
Now for some technical information and further explanation of the firing cycle. You may wish to use the animation below for reference. While the solenoid rests idle, the front portion of the ram housing is pressurized, which holds the ram in the rear position. The Nerve's air chamber is filled with pressurized air, ready to be released when the ram fires. To fire the marker, the solenoid energizes and switches its internal valve, which is pneumatically connected to the ram housing (as mentioned). This causes the front of the ram housing to vent its pressure while at the same time the rear of the ram becomes filled with pressure. This action drives the ram forward.
Once the ram reaches the front position, it pushes open the valve poppet (aka cupseal) which opens the marker's main valve. The valve opening will release pressure stored in the air chamber into the valve, where it is shunted up and out through the bolt, firing the ball. After the dwell time expires, the solenoid switches back, which vents the rear of the ram and pressurizes the front. This retracts the ram and bolt into the rear "idle" position. Without the ram holding it open, the valve poppet shuts itself and seals off the release of air.
The marker's ram will be actuated upon the venting/pressurizing that's operated by the solenoid valve. The most important factor here is the use of the dwell time, which is the time the solenoid remains energized, which translates to how long the ram takes to move forward and release pressure. The dwell setting must be set high enough to allow the ram to cycle forward and dump pressure to fire the ball. This is my definition of dwell and what it is used for.
With all that said, here is the Nerve animation.
Click here for a slower version.
Pressure/Force Dependency:
The hammer/valve design is very simple, however it, like everything else, has its own advantages and disadvantages. The way the valve functions is by applying force to the back of the valve poppet, which physically forces it open. The trick here is the air pressure that exists within the marker, and how it interacts with other parts.
In order to understand this dependency, you need to have a basic understanding of what pressure is, and how it works. Pressure is defined as pounds-per-square-inch which means you can take the surface area of an object (in square inches) and multiply it by the pressure pushing on it, and this will yield how many pounds of force is being acted upon the surface. This is important in hammer/valve markers because there is much more surface area holding the valve shut than there is pushing the ram forward. Specifically, there's 50 pounds holding a Nerve's valve shut, whereas the Nerve ram only excerts 10-15 pounds of force. The question is, then, how does the ram push the valve poppet open?
The answer is because the actual amount of force the ram exerts is more than the product of air pressure pushing on it. The ram also utilizes a stroke length which allows it to accelerate (in theory; please read the note below) and push on the valve with more force. Specifically, the movement of the ram into the forward position is swift enough that the initial force is doubled or more, which is enough to open the valve and fire the ball. It's for this purpose that the marker is equipped with a heavyweight hammer at the rear. This adds to the momentum and provides a boost in force required to actuate the valve.
The hammer/valve "balance" exists because after a few milliseconds the mechanical force addition that the ram used to open the valve will be lost, because the ram stops moving once it reaches the forward position. Due to this, the valve poppet tends to shut itself after the momentum of the ram dissipates. The hammer/valve balance is such that the marker's ram will be retracted immediately after the valve shuts itself. The closing motion of the valve assists in the ram's rearward movement and allows it a noticeably tighter response time, as well as heightened performance.
In other hammer/valve designs the hammer is traditionally located in front of the piston, where the hammer itself strikes the valve. However, the Nerve design is a bit different. The valve and piston pieces, which are normally separate, are combined in a Nerve and the hammer is relocated to the rear of the assembly. There were several design reasons for this but I won't go into too much detail, the main reason being easy of assembly and disassembly.
Please note that I mentioned the ram accelerating in theory only. In practice the ram's speed remains constant (much like the speed of many other moving parts in a paintball marker). This is because the speed of the part is limited by how quickly air pressure on the other side of the piston can vent into the atmosphere. In the case of a Nerve, it means the air pressure that was used to hold the ram in the rear position takes some time to vent out. The ram is pushed forward by air from the solenoid but it can only push hard enough to move the ram a little bit at a time, due to the compressing air that's being vented out.
To put this in terms that can be understood, imagine the dwell time for a Nerve being 10 milliseconds (ms for short). At any given dwell time, the first 4/5 of it is taken up by the ram moving to the front position. This is due to the speed at which air can vent from the front of the ram, allowing it to move forward. During the last bit of time the valve is opened and air released to fire. The ram then takes another equivalent to the dwell time to return to the idle position.
Similar numbers can be found on many other single-stroke markers as well (all markers without a separate firing poppet). This is a small technicality that limits all paintball markers, and isn't too important in practice, but is worth mentioning to help give people a better understanding of exactly how a marker functions.
Pressure and Dwell Concerns:
Nerves, like some other hammer/dwell designs, operate under the use of an LPR (low pressure regulator) to drop the pressure feeding the solenoid/piston lower than the air used to fire the ball. The purpose of this is to allow a decrease in dwell with a high input pressure to yield the maximum efficiency possible, while at the same time using the LPR to eliminate the natural consistency problem that usually occurs when the dwell is lowered.
However, this is easier said than done. While adjusting the marker it becomes quickly apparent that there are many combinations for successful operation. In brief this would be any LPR pressure combined with any input valve pressure, at any dwell time. if each of those factors had 10 possible increments, then there would literally be 1,000 different ways to set the gun.
Increasing one variable can often be compensated by altering another variable (although there are working limits to this) however as with all things there are exceptions to the rule. Below are some tendencies that can be derived from the operation of the marker. Some of these can be applied to other hammer/valve electropneumatics s as well.
· Increasing the input pressure will increase the energy used to fire a ball however it will also provide more force against the valve. High input pressures tend to work best with a low dwell time and moderate LPR pressure. You can also switch and use a low LPR pressure with a slightly higher dwell time, but this doesn't often work with a Nerve since the hammer weight is non-adjustable (some other markers offer aftermarket hammers to allow for different stroke weight, accustomed to different settings). You can use a high and low combination of dwell/LPR however the results may not be good (for example, high input pressure / high dwell / really low LPR, or high input pressure / really low dwell / high LPR).
· Increasing the LPR pressure will add speed and momentum to the ram, allowing it to open the valve more quickly. Consequently, cycle rate can suffer at low LPR pressures due to the longer time the ram takes to move forward. Coupled with a higher LPR setting is a lower input pressure with longer dwell, which may yield poor efficiency due to the low input pressure.
· Increasing dwell time will add more volume of air used to fire the ball, naturally reducing the dwell setting, however this tends to greatly reduce efficiency. Higher dwell settings generally require less LPR pressures due to the valve being opened longer.
Many users have found it easiest to arbitrarily [initially] set the dwell setting to an amount then experiment with different LPR and input pressure combinations to see what works good, and modify the dwell time if needed. This can be a long process but a completely tuned marker will function very well.
Related Links:
· Firing assembly
· LPR assembly
· Solenoid