In a hydraulic hybrid system, one pump is powered by a truck’s engine to pressurize the system. The remaining two pumps connect with one rear wheel each, which enables them to capture braking energy and use this stored energy to accelerate the vehicle later on. Special components called accumulators are responsible for the actual capture and release of braking energy. When a truck driver depresses the brake pedal, the two pumps connected with the rear wheels convert the moving truck’s kinetic energy into hydraulic power. The conversion process causes the truck to decelerate, and the resulting hydraulic energy is stored in the accumulators for later use. When the accelerator pedal is depressed, hydraulic energy is released from the accumulators to propel the truck forward.