Re: Diesel EMD SW7 "Calf" - use?

A Calf is always used in conjunction with a Cow. It is a way to add additional HP and tractive effort to a switch engine. SW Calfs have a low body so the crew can see over them, at least more so than over a cow. A typical consist has one cow and one or more calf. By only having a single cow the crew can see over all the calves and have better visibility.

A slug has no prime mover (diesel engine), a calf is like a B unit, it is a full locomotive with no controls.

Matt,

EMD sold 'cow & calf' sets as 'transfer' engines. The SW7 'cow & calf' were sold as a permanently drawbar'ed 'set' known as a TR4. The NW2 'cow & calf' set were sold as a TR2. These engines were bought as transfer or hump yard engines, but many were later split up, or converted to cab unit 'cows'(CB&Q). C&O bought 'cow/calf/calf' sets at one time..... The 'calf' unit was just a 'non-cab' booster unit, it had the diesel engine and electrical system, just no control cab for the crew. Some railroads built 'slug' units; these were units with only the electrical system, no diesel engine. They took electrical power for the main generator of the 'cow' or 'mother' unit. They provided extra TE, and low speed for yard/transfer operations.

Jim Bernier

Matt & Kathleen Brennan wrote:

Southern Railway Systems (now part of NS) used calf/slug configurations. Have a read and look:

Stew

Incorrect. The 'calf' is just a 'B' unit for a switcher. It is complete except for a control cab (actually, they often DO have limited controls, just like most 'B' units).

What you are referring to is a 'SLUG", not a 'calf'. Slugs have no Diesel engines, just traction motors.

Dan Mitchell ==========

VManes wrote:

I don't know if Oliver operated in any of the Michigan iron mines or not.

They DID operate at several mines in Minnesota. I saw the Baldwin cow and calf sets used to haul raw ore out of the open pit mines to the crusher/concentraters, ca. 1960. One such mine was the "Sherman" pit. They operated on VERY poor temporary trackage that was moved about like snap track to wherever the shovels were working at the time. The cars used were air operated side dump cars (Difco?), about ten per cow-calf set. The grades in the pits were steep. The Baldwins were good 'luggers'.

Dan Mitchell ==========

Mark Newt>

Sorry Dan, it was Minnesota that I meant to type, not Michigan... I reckon the Baldwins would be well suited to that sort of service.