Final answer:
Journal entries for Sheffield Company's transactions must account for maintenance expenses, equipment trade-in, land exchange without commercial substance, and capitalization of an equipment upgrade.
Step-by-step explanation:
The question posed pertains to a series of transactions involving property, plant, and equipment for the Sheffield Company and requires the preparation of journal entries to accurately register these transactions in the company's books. Given that the transactions include maintenance costs, equipment trade-ins, land exchanges, and major equipment upgrades, the entries must reflect the financial changes according to accounting principles. Maintenance costs will be recorded as expenses, traded equipment will involve removing the old asset and recording the new one at fair value minus the trade-in allowance, land exchange will be recorded at the book value because the exchange lacks commercial substance, and upgrade costs will be capitalized and added to the equipment's value.