However, the maximum pressure is limited to atmospheric pressure, so that all the equipment has to be much larger and heavier to compensate. This disadvantage is made worse at high altitude. The vacuum brake is also considerably slower acting in both applying and releasing the brake; this requires a greater level of skill and anticipation from the driver. Conversely, the vacuum brake had the advantage of gradual release long before the Westinghouse automatic air brake, which was originally only available in the direct-release form still common in freight service. A primary fault of vacuum brakes is the inability to easily find leaks. In a positive air system, a leak is quickly found due to the escaping pressurized air; discovering a vacuum leak is more difficult, although it is easier to repair when found because a piece of rubber (for example) can just be tied around the leak and will be firmly held there by the vacuum.