GB2024357A - Improvements in drain rod couplings - Google Patents

Abstract

A drain rod coupling has a male threaded spigot 36 rotatable on a pin 30 carried in one end ferrule, and a square head 34 to the pin to engage in a like socket at the end of a female threaded bore at the end of another coupling part. The head and socket hold the parts angularly whilst the spigot is rotated to engage the screw threads. Compatibility with like prior couplings is maintained by keeping head, socket and thread sizes constant, but stronger pins are provided by increasing the shank diameter and using a radial projection 32 between head and shank to hold the spigot in place. <IMAGE>

Description

SPECIFICATION Improvements in drain rod couplings This invention relates to drain rods and the like, and more particularly to couplings for the same.

Drain rods comprise a series of separate rods, typically of the order of 3ft long, which are required to be connected together in an indefinite length according to requirements. It is particularly important that couplings should not become released when the rod is in use, since otherwise, instead of the drain rods being used to remove obstructions, the detached part of the rod may form a further obstruction.

One known form of coupling for this purpose comprises a ferrule or cap at each end of each section of rod, one ferrule on each rod providing a female screw-threaded portion; and the other providing a male screw-threaded portion. With such a simple coupling, it is necessary for the rod to be continuously turned in the direction which tends to screw the male portions more firmly into the female portions throughout the whole of the use of the rod, and any reverse rotation is likely to cause disengagement at an arbitrary point along the total length of the rod.

A more secure coupling of the same kind has the male threaded portion provided on a rotatable spigot which is held to an end of the rod by a pin which extends generally axially and passes through the spigot The pin has an enlarged head to hold the spigot in place axially, and the head is of non-circular configuration. Hitherto, the pin has been made from square cross-section material so as to provide the head of the pin from the material without any subsequent operations, and the remainder of the length of the material to form the pin has been turned down so as to be of circular cross-section and smaller at all points than the head. The female threaded portion terminates inwardly of the end of the ferrule in a socket of complementary cross-section and dimension-to the head of the pin.The male threaded portion is integral with a non-circular part typically of hexagonal cross-section and of smaller transverse dimension than the diameter of the ferrule, and a spanner or the like can be used to rotate the male portion to screw it firmly into the female portion, the two ferrules being held angularly fast to one another by the engagement of the pin head in the socket. This arrangement is found to be very satisfactory in use, particularly with conventional rods made of bamboo or cane.

However, drain rods are now often made of plastics materials which are capable of much greater flexibility than cane (itself an advantage) and which can be made in longer lengths, and this can place much more stress on the pin. If the pin breaks, the spigot can slide off the pin and the rod sections become detached.

In attempts to design couplings of greater strength and resistance to breakage, a problem is encountered if it is desired to make the new couplings compatible with and usable with the existing couplings -- as may be the case for example where the user requires to buy a few new rod sections to use with some existing older rod sections. In this case, the freedom of the designer is limited in that the dimensions of the head of the pin and the complementary socket are fixed, as are the screw-thread sizes.

The object of the invention is to solve this problem by making a stronger pin whilst maintaining compatibility.

In accordance with the present invention, a drain rod coupling of the kind comprising first end fitting including a pin with a non-circular head, a male threaded spigot supported on the pin and provided with means facilitating rotation of the spigot thereon, and a second end fitting having a complementary female threaded bore and a socket to receive the pin head non-rotatably, is characterised in that a radially projecting shoulder is provided between the head and the shank of the pin.

This enables the shank which forms the spigot supporting portion to be made of larger diameter, without freeing the spigot from its axially captive position on the pin, and thus enables an essentially stronger construction to be provided.

Preferably the pin is made by cold forging, from a rod originally of the same diameter as in the finished shank, but the material being displaced outwardly to provide an integral shoulder as well as being deformed to provide the non-circular end portion or head. The head may in fact be smaller than the spigot supporting portion, instead of larger.

One presently preferred embodiment of the invention is now more particularly described with reference to the accompanying drawings wherein: Figure 1 is a fragmentary view showing a pair of drain rods coupled together; Figure 2 is a sectional elevation of one coupling part; Figure 3 is a view in the direction of the arrow A in Fig. 2; Figure 4 is a sectional elevation of a second coupling part and, Figure 5 is a view in the direction of the arrow B of the second coupling part.

Turning now to the drawings, particularly Fig. 1, the adjacent ends 10, 12 of a pair of drain rod sections are provided with coupling parts 14, 1 6 respectively. Each of these parts 14, 1 6 is provided with a socket 18 to receive an end of the rod section, and can be fixed to the rod section in any convenient manner.

The part 14 is provided with a female screw threaded portion 20 which terminates at its inner end 22 in a non-circular socket 24. As illustrated in Fig. 3, the socket may have parallel side walls 26, 28.

The second coupling part 1 6 has a pin 30 fixed to its end, the pin being integral with a radial flange or projecting shoulder 32 and with a head 34 which as best seen in Fig. 5 is (in this example) of square cross-section. The parts 30, 32, 34 may be made by cold forging a rod of the same diameter as shank part 30, so as to upset the material and create the flange or shoulder 32 and possibly at the same time create the square head 34. The pin may be fixed to the coupling 16 in any convenient manner.

Between the flange 32 and the body of the coupling 16 is located a spigot 36 comprising a male screw-threaded portion 38 and a hexagonal or nut portion 40 made integrally with the portion 38. The spigot is confined axially against loss, but is free to rotate on the pin 30.

The flange 32 -is of smaller diameter than the screw-threaded portion, so as to offer no obstacle to engagement of the male threads 38 with the female threads 20, and preferably the hexagonal portion 40 is of smaller transverse dimension at all points than the body of the coupling parts 16. The pin 30 may be made of any required diameter, and in particular can be made larger than the head 34.

Claims (4)

1. A drain rod coupling of the kind comprising a first end fitting including a pin with a non-circular head, a male threaded spigot supported on the pin and provided with means facilitating rotation of the spigot thereon, and a second end fitting having a complementary female threaded bore and a socket to receive the pin head non-rotatably, characterised in that a radially projecting shoulder is provided between the head and the shank of the pin.

2. A drain rod coupling as claimed in Claim 1 wherein the head of the pin is of square crosssection and is smaller than the shank.

3. A drain rod coupling as claimed in Claim 1 or Claim 2 wherein the pin is a cold forging formed integrally with the radiai shoulder and head.

4. A drain rod coupling substantially as described with reference to the accompanying drawings.