tiller bubble windows
Some tractor drawn aerials are built with bubble windows in the tiller doors. These windows are designed to increase the field of vision for the tiller operator without having them open the door or window to look down the sides of the apparatus. Tiller cabs are designed to be narrower so it’s not difficult for the tiller operator to steer and look out the window at the same time. Generally you have to specify with the manufacturer that you want this option for the tiller door windows. Pierce now makes all their tractor drawn aerials with tiller bubble windows as the standard. (Click to enlarge)
The need to look out down the side of the apparatus is a common practice and using these types of windows can be extremely helpful during cold or inclement weather. The tiller operator is protected while simply popping their head out into the bubble to get a better view. Here are two examples of looking out down the side of the apparatus using bubble windows. The first example is from an American LaFrance while parked on the street, the second is from a Simon duplex that was parked on the apparatus floor. (Click to enlarge)
bubble window depth
Bubble windows can come in different depths, therefore, you want to make sure that the depth is deep enough to achieve the desired effect of increased visibility.