Re: Ice Reefer Conversions to Mechanical?
From reading in the files of my railroad I will add to what Tony has correctly stated and add - at the time mechanical refrigeration units became viable -
market conditions on all sides of the rail shipment were also changing.
Frozen and fast frozen was where the market was evolving and had been for some time. Frozen food had been around for some time.
However it had taken some time to catch on to where the volumes were significant. (1) This was because corner markets - not super markets were the most common. And these Ma & Pa stores did not have large areas to receive, store, and display frozen foods. Larger markets had to come into general being and that did not happen in a broad way until the mid to late 50's. Food distribution centers capable of holding these large volumes of frozen food were also being built as these super market chains made their presence known.
(2) Once the volume of these frozen foods became significant to the railroad industry, HI reefers (high insulation) were now what the industry wanted and the railroads (or reefer consortiums of the railroads) that could supply the highly insulated cars were the ones that got the shipment. Of the high insulation reefers, they were on the scene in the mid to late forties, however there was not a big enough market at that time to over shadow the global refrigerator car makeup on the whole, so the current wood fleet soldiered on.
By the time a dependable mechanical unit was developed in Bloomington, MN, my railroad did send some folks over to check it out. And they did look at the financial ROI * of converting/rebuilding older reefers and that was a no go almost immediately as much of the fleet was already old. In the financial make up of things, building new cars provided the best return on investment. And (3) the car builders had shifted to all steel car building for some time now.
And as Tony listed, the cars were 40 footers, with six foot doors. By this time, 50 foot cars with doors and floors built to handle pallets and pallet unloaders were what the industry demanded.
* I may have stated this before however it bears repeating often. Railroads were just a vehicle for their owners to make money. We forget that far, far, too often.
Jim Dick St. Paul, MN