13,908. Thompson, W. P., [Strectt, J. C., and Shields, G. H.]. June 9. Cleaning externally.-In a device for cleaning the exteriors of ammonia condenser and other pipes, of the type in which cutters are mounted in the halves of a cylinder adapted to be detachably arranged to enclose the pipe, and rotated thereon, means are provided, such as a bar with rollers, adapted to engage one or more adjacent pipes, to prevent rotation of the member that supports the cylinder and carries the operating-mechanism. A cylinder carrying cutters 23 is made in halves 2 hinged together at one side 3, and adapted to be tightly closed about the pipe 10 and locked at the opposite side. Each locking-device comprises a catch 14, Fig. 7, pivoted to the fulcrum pin 12 of a lever 13, the pin 12 being capable of a sliding movement in slots 15 formed in one half-cylinder. The other half-cylinder has a pin 7 engaged by the catch 14, and a friction plate 21 against which one end 18 of the lever 13 bears when the other end 19 is depressed, thus tightly closing and locking the edges of the half-cylinders by a toggle action. Each preferably integral series of cutters 23 is housed in a recess with the cutting-edges projecting within the cylinder to engage the scale &c. to be removed. The cutters are mounted on pins 24 at an inclination to the axis of the cylinder, so that the cutters feed the device along the pipe as the cylinder is rotated. The ends of the pins 24 are held in slots by means of bifurcated spring plates 33, and outward movement is limited by screws 35. The cutters are kept clean by a plate 36 with teeth projecting between and conforming to the shape of the cutting-edges. For initially removing sufficient scale to allow the cylinder to pass, adjustable cutters 27 are carried at one end of the cylinder, and their outer cutting-edges 29 serve, if necessary, to remove abnormal deposit of scale from adjacent pipes. Removal of scale from the pipe 10 is completed by scrapers 31 carried at the other end of the cylinder. Openings 38 are provided to allow escape of removed scale from the interior of the cylinder. Each half-cylinder has ribs 39 of T-section adapted to work in corresponding grooves in semicircular supporting yokes 41 projecting from a cross-bar 43. A shaft 45 passing through a hub on the cross-bar, and rotatable through reversible ratchet mechanism by a handle 52 the length of which is adjustable, carries a bevel gear-wheel 46 meshing with a bevel 47 in two parts carried by the halfcylinders 2. The shaft 45 also passes through a slot 57 in a member 53 adjustably clamped to the bar 43 by a washer-plate 54 and nut 55. The member 53 carries a roller 60 bearing against a pipe 30 adjacent to the pipe 10. A tubular arm 64 carried by a pin 62 on the member 53 can be locked by a spring bolt 84 parallel to, or as shown, at right-angles to, the pipe 30. Adjustable in the member 64 is a spindle 65 carrying a roller 68 which can be locked by a spring bolt 82 with the roller 68 parallel to, or as shown, at right-angles to, the pipe 30. The roller 68 bears against the pipe 30 under pressure of a spring in the member 64. Rotation of the vokes 41 about the pipe 10 is thus prevented. In the position in which the cylinder can be opened as shown in dotted lines, it can be locked against rotation in the yokes 41 by a spring bolt 85. The reversible ratchet mechanism comprises a toothed ring 50 secured to the shaft 45 and housed within the hub 97 of the handle 52, and a pawl 51 projecting from a piston 95 slidable in a cylindrical chamber on the hub 97. The chamber is closed by a cap 98 through which passes a shank 99 on the piston 95. A cap 101 is secured to the shank 99 and between the caps 98, 101 is a slidable and rotatable bush 100 from which projects, on opposite sides, pins 106, 108. The pin 108 enters one of a series of holes in the cap 101. The pin 106 enters one of two holes of different depth in the cap 98. As shown, the pin 106 is in a hole of such depth that the heel of the pawl is just clear of the ratchet teeth 50, so that the handle 52 only drives the shaft 45 in the direction of the arrow. To reverse the drive, the cap 101 and with it the pawl 51 is pulled outwards and rotated through 180 degrees, in which position the pin enters another hole in the cap 101. To lock the mechanism to drive in both directions, the bush 100 is moved to disengage the pin 106 and is then rotated until the pin registers with a deeper hole in the cap 98, thus allowing the pawl 51 to move further towards the shaft 45 so that the heel of the pawl engages the teeth 50. The pawl 51 and bush 100 are urged inwards by springs as shown. The apparatus may be motor driven, a suitable motor being secured to a lug 110, and the handle 52 replaced by suitable gear. In a modification, the washer plate 54 is omitted, the member 53 is clamped in a recess in the bar 43, and the rollers are carried on pintles which are secured in holes in one arm of an L-shaped member by a set-screw and spring bolt respectively, the other arm of the L-shaped member having a projecting pin by which it is secured to the member 53, and a spring bolt securing the pin in a boss on the member 53. A simple form of non-reversible ratchet is also employed. In a further modification, the member 53 is replaced by a straight bar carrying rollers at its ends adapted respectively to bear on the same side of the adjacent pipes above and below the pipe being cleaned, the bar with its rollers being pressed towards the pipes by a spring between the bar and the hub of the handle 52, which is rigidly secured to the shaft 45. The Specification also describes modified forms of cutters, and of means for securing the cutters and for locking the halves of the cylinder together. A lever tool is also described for drawing together the halves of the cylinder to facilitate the locking operation.