The type of door that will work best for your shower depends on the design of your shower, the size of the opening and the practical space considerations that determine how your door should open. Showers generally fall into three types of designs.
Preload is the tension created in a fastener when it is tightened. This tensile force in the bolt creates a compressive force in the bolted joint known as clamp force. For practical purposes, the clamp force in an unloaded bolted joint is assumed to be equal and opposite of the preload.ither is acceptable, however a torque value defined for tightening the head does not necessarily apply to tightening the nut. Tightening the head vs. the nut can result in different nut factors and therefore change the torque required to achieve proper preload.
Load is a term for how hard the device has to work to power whatever is attached to it. High load means the output power is high, low load means the output power is low. You can increase the load by, say, connecting a second device to the output of the generator. Assuming the voltage is constant, the current will be higher (since there are now two deices powered by the generator). That means that the equivalent resistance of both deices in parallel will be lower than that of a single device. So, increasing the load means decreasing the resistance of the load. This may be counter intuitive, but usually devices are not rated in resistance-they are rated in input current or power, so the load follows that.