The Andrews was one of the first truck designs to employ cast frames. Andrews trucks used separate journal boxes, and could be identified by the steel bar between the truck sideframe and the journal box base. A big selling feature of the Andrews design was that journal boxes from older archbar trucks could be reused in new Andrews trucks.
Trucks employing the Andrews design were built by various manufacturers (Bettendorf, et al) from around 1910 through the 1930s. Andrews trucks were banned from interchange service in 1954, although by that time that were only used in lighter applications (refrigerator cars, cabooses, etc). Andrews trucks are probably still in use today on MOW cars and by logging railroads.
N scale Andrews freight trucks are available from Atlas and Micro-Trains -
N scale Andrews "leaf spring" caboose trucks are available from Bachmann. This style of truck came onto the scene in the mid-teens and was popular through the 1940s -
Atlas - wheelbase 10.5mm, frame width 15.85mm, wheel size 33", axle length 14.15mm
Micro-Trains - wheelbase 10.3mm, frame width 16.8mm, wheel size 33", axle length 13.7mm