Part of a small array of hand tools displayed in "America On The Move" - such tools were used in the inspection and repair of steam locomotives. Light repairs on steam locomotives were usually done in roundhouses at the many small locomotive terminals throughout a railroad's system; heavy repairs were done in a large, centralized repair shop serving the whole system (often referred to as the "Back Shop"). Most of these tools date from the early- to the mid-20th century, roughly 1900-1955.
A car inspector or car oiler used this journal hook to inspect journal boxes and bearings of railroad cars and locomotive tenders; he could more easily open and close a journal-box lid with this hook, without having to stoop down. A journal box held the plain bronze bearing and outer end of a railroad-car axle.
If, while running down the railroad track, the bronze bearing and axle overheated for lack of oil, a 'hot box' quickly developed.
The heat of friction of the oil-starved bearing and axle ignited the cotton pad inside the journal box that normally kept oil flowing to the bearing. If the train did not stop immediately, the rapid build-up of heat could destroy the bearing and probably cause a severe derailment.
Therefore railroad-car journals and their oil levels had to be inspected every few hundred miles. It took legions of car inspectors and oilers to do this work. Today, modern roller-bearings on railroad freight cars require maintenance only every 100,000 miles or so, and 'hot boxes' are extremely rare - almost non-existent.
Journal hooks were used by mechanics in locomotive-repair shops and in roundhouses, by car inspectors in railroad-car repair shops, and by car inspectors in passenger-car and freight-car yards.