Close Joint

This will be found noticed under Tight Joint.

Collar Joint

Long rings or detached sockets with internal threads connecting lengths of iron barrel, tie-rods, etc, are termed collars, and form collar joints. Lengths of copper or wrought iron chain-bar, 2 in. or 3 in. wide by - in. thick, built into stone architraves, or round towers, domes, etc, and secured to each stone by stubs leaded in, are sometimes joined to each, other by means of collars of the same metal, likewise leaded into the stone to receive the turned-down ends of the bars, which, however, should always be in as long lengths as possible, the joints invariably being over the columns in the case of entablatures. When of large size, collars used in piping are not threaded, but fixed by caulking so as to cover the butting edges of two spigot ends, the collar being easily slipped over the pipe and back again over the joint after a piece has been cut out to make room for a T-piece. A very efficient kind of collar has been used for uniting large waterpipes or mains. The pipes are cast with both ends beaded and no socket. These are butted together and each contiguous pair of beads surrounded with a well-tallowed band of felt about 6 in. in width, and this is again encompassed with a cast iron collar made in 3 or 4 flanged segments, which are bolted together, closely gripping the beads and forming a tolerably inexpensive, sound, and somewhat flexible watertight joint.

Corked Joint

This has been already explained under its alternative appellation of Caulked Joint.

Cottered Joint

Cottered Joint is formed by means of two folding iron wedges called cotters, which have a "draw," and pass through slots made in the plates or flattened-out ends of the rods or parts they unite. In order that the cotters may glide smoothly on their seats, wrought iron shields called gibs, having turned-up ends to clutch the ends of the slots, are inserted in them, as shown in Fig. 32, which represents the gibs and cotters of a strap upholding a tie-beam to a king-post. Sometimes a single cotter is used without gibs. The angle of obliquity of the cotters, in order to be safe against slipping, must be very little, and should not exceed 4°, which is the angle of repose for greased surfaces of iron upon iron. Cottered joints are used for adjusting the length of tension rods, diagonal ties, king . bolts, etc, the ends of these pieces being either forked to seize exteriorly the parts to which they are fastened, or else flattened out and inserted between their sides, the cotters and gibs passing through all. In the attachment of tie-rods, the cotters often go directly through a slot in the cast iron shoe to which the rafter is bolted. The shoe may be either on the cap of an iron column, or on the top of a wall, or it may be bolted to the inside face by means of a horizontal bolt secured to a plate outside and passing right through the wall. If the shoe rests on the top of the wall, it is secured to a stone block with lewis or dovetail bolts leaded thereto, or else vertical bolts with corkings are built in the brickwork that traverse holes drilled in the stone as well as others in the shoe, which is then firmly bolted down. If provision has to be made for expansion, it is done as described under Expansion Joint. Where no adjustment is required, the end of a stay bar may have a loop so made as to pass over a socket, through a slot in which a cotter is driven to confine it.