Battery electric factory flat trucks are small, battery powered flatbed factory runabouts, which were popular before forklift trucks. They are actually quite different than milkfloats, and performed a useful, but generally unseen role in construction in Britain.

General layout

A factory truck is a small, manouverable and low-height flatbed truck, ideal for carrying fairly heavy or numerous objects. They have 4 small wheels under the flatbed, with the battery box between the axles. At one end, they are driven. The drive comes from a prop shaft running down between the 2 halves of the battery box, down the middle of the vehicle. At the other end are the steered wheels, with the motor between them, driving the prop shaft. Also at this end is the drivers platform. This consists of a floor with a on/off footpedal, which when pressed releases brakes and applies power. There is a control box and direction selector on one side, and a narrow-boat style tiller on the other for steering. Usually this moves left to right, but notable Electricars vehicles had tillers that went up and down.
Some useful views of a vehicle made by Greenbat can be found here: http://www.pogo.org.uk/railway/gandbtr.html

Batteries

Like most industrial battery vehicles, the batteries are lead acid, made up of 2 volt cells. These are split into a bank on either side of the prop shaft, and are a major running cost when they wear out, usually about 10 years.

Why use them?

These vehicles have many advantages over similar internal combustion or railway ones. They do not produce hazardous emissions, making them ideal for inside, they can go virtually anywhere in the factory (not needing rails to guide them), and their small size relative to a milk float or pickup truck means they can get in smaller places. They can also be driven in either direction from one end, and the foot brake/power on pedal means if the driver falls off, the vehicle stops.

Are there any left?

As well as the one listed above, I know of 4 others. An Electricars is to be found hiding on a preserved line in England, and at a secret location in Derbyshire there are 3 more: and Electricars model TU, a Brook-Victor model H2 (from Terrys chocolate factory in York, fitted with an electromagnetic controller) and a 1.5 ton Greenbat.