CHAPTER V.Stems and Handles.

Having discussed the various forms of renovators in detail, the next appliance to be taken up is the connection between the renovator and the cleaning hose, this being the next portion of the apparatus forming a conduit for the dust-laden air on its way from the renovator to the atmosphere on the exhaust side of the vacuum producer.

In order that the renovator may be moved about on the surfaces to be cleaned, a rigid handle must be provided and, in order that these various surfaces may be reached while the operator remains in a standing position, it is necessary that this handle be of considerable, as well as variable, length. Also, a passage for the dust-laden air must be provided in connection with this handle. These conditions are best met by a metal tube, which the author terms the stem.

These stems have been made of various metals, that first used being drawn brass, probably because it is best suited to be nickel plated. On the earlier systems they were almost invariably made of No. 16-gauge tubing, ⁷⁄₈-in. outside diameter, and were bent at their upper end through an angle of nearly 135° in order that the hose would hang from the stem vertically downward, when the stem was held at an angle with the floor of 45°.

The lower ends of these stems were rigidly attached to the renovator in such a manner as to assume the above-mentioned angle with the floor when the renovator was in the proper position for cleaning. In order to bring the curved portion of the stem hand high, the stem was made approximately 5 ft. long.

When operated with Type A carpet renovators, these curved stems were apparently satisfactory. However, when they were used in department stores, and other places where much barefloor cleaning was necessary, the stems were cut through at the curved portion by the sand blast action of the dust. The cutting of these stems in bare floor work, while they were satisfactory in carpet cleaning, indicates that the velocity in the stem, due to the large volume of air passing the bare floor renovator, was too great for this soft metal to withstand the impact of the dust on the curved surface. With the systems in use at that time no means were provided to control the vacuum at the vacuum producer and the hose and pipe lines were small, both of which tended to cause a wide variation in the volume of air exhausted under various conditions, in the character of surface cleaned, and in the number of renovators in use. Therefore, the value of this destructive velocity is not readily obtainable. However, the author considers that, in extreme cases, the quantity of air passing through these stems may have been as high as 55 cu. ft. per minute. As the inside diameter of the stems was ³⁄₄ in. the area was 0.44 sq. in., or 0.00328 sq. ft., and the velocity through the stem was nearly 17,000 ft. per minute. With an average air passage of 40 cu. ft. per minute the velocity was 12,200 ft. per minute.

Referring to tests of carpet renovators,Chapter III, it will be noted that the maximum volume of air passing through carpet renovators of Type A was 33 cu. ft. per minute, which gives a velocity of 10,000 ft. per minute. Apparently, at this velocity, the cutting action, due to the impact of the dust on the curved surfaces, was not severe. However, the author considers that the maximum velocity that should be permitted through these stems is 9,000 ft. per minute.

As the dirt picked up must be lifted almost vertically, the velocity in the stem must not become too low or dirt will lodge in the stem. Experiments made by the author indicate that the minimum velocity should be at least 4,000 ft. per minute, in order to insure a clean stem at all times.

Shortly after the introduction of vacuum cleaning, the use of drawn-steel tubing for the manufacture of stems for cleaning tools was standard with one manufacturer and, lately, its use has become almost universal, except in cases where very long stems are necessary, as on wall brushes when cleaningvery high ceilings. For such work, aluminum stems have been adopted.

This harder metal will better withstand the cutting action of the dust and can also be made much thinner and lighter in weight than brass tubing of equal strength. These stems were made from 1 in. outside diameter, No. 21 gauge tubing, having an internal area of 0.68 sq. in., and the author does not know of any cases where these stems have been cut by the impact of the dust.

Stems of this metal are recommended by the author for use with all floor renovators and with wall brushes, except in cases where exceedingly long stems are required, when those of drawn aluminum tubing are recommended.

For use with Type A renovators, where the minimum air quantity is approximately 22 cu. ft. per minute, the greatest area permissible is224000= 0.0055 sq. ft., or 0.79 sq. in., equivalent to 1-in. diameter. With a maximum air quantity, under proper control, of 39 cu. ft. per minute, the minimum area will be399000= 0.00433 sq. ft. or 0.625 sq. in., equivalent to 0.89 in. diameter, so that a 1-in. outside diameter stem of No. 21 gauge metal, having an inside diameter of 0.932 in., is recommended.

For use with a Type F renovator, with a minimum air quantity of 44 cu. ft. per minute, the maximum area of the stem will be444000= 0.011 sq. ft., or 1.58 sq. in., equivalent to 1.4 in. diameter, while, with a maximum air quantity of 70 cu. ft. per minute, the minimum area will be709000= 0.0077 sq. ft., or 1.11 sq. in., equivalent to 1.18 in. diameter, and a 1¹⁄₄-in. diameter stem of No. 21 gauge metal, having an inside diameter of 1.18 in. is recommended.

Tests of Mr. S. A. Reeve, which are discussed inChapter III, indicate that both edges of the cleaning slot on any renovator must be in contact with the surface cleaned in order to do effective cleaning. A renovator which is rigidly connected to its stem can be effectively operated with the stem at but one angle with the surface cleaned, which makes the cleaning under furniture, or on wall at various heights above the floor, impossible. In order to do effective cleaning with any degreeof speed and comfort to the operator, some form of swivel joint between the renovator and its stem is necessary.

These swivels have been made in many forms, one of which consists of two hemispheres connected by a bolt on their axis, as shown inFig. 37. This form of swivel is unsuited for use under these conditions, as lint, thread and any other small articles picked up will catch on the bolt which lies directly in the path of the dust-laden air current, and its use should be prohibited in all cases.

FIG. 37. FORM OF SWIVEL JOINT CONNECTING STEM TO RENOVATOR.

Another form of swivel, which is must better than the last mentioned, is shown in the illustration of the bare floor brush,Fig. 26, Chapter IV, there being no obstruction in the air passage. However, these swivels are composed of moving parts which are in contact with the dust-laden air and great care must be taken in their design so that in action dust does not lodge between the wearing surfaces and shortly ruin the swivel. This can be guarded against by making any opening between the parts of the swivel point away from the dust current, as indicated inFig. 38, in which the direction of the air current is indicated by the arrow. A slightly loose fit between the wearing surfaces will permit a small leakage of air through the joint which will tend to remove any dust which may find its way into the joint. However, it is not considered advisable either to allow very much leakage through the joint, as it reduces the net efficiency of the system, or to depend much onthe air current through the joint keeping the wearing surfaces clean. The swivel indicated in the illustration of the floor brush does not entirely prevent the dust entering same and it permits the movement of the stem in a vertical plane only. On the other hand, a swivel consisting of a 45° elbow, rigidly attached to the stem and turning freely on a horizontal spud, and fastened to the renovator, as shown inFig. 38, allows a motion of the stem either in a vertical plane, which will cause the renovator to rotate, and enable the operator to pass same around or back of legs of furniture, or a semi-rotary motion may be imparted to the stem, which will permit the renovator to move forward in a straight line while the angle which the stem makes with the floor will constantly decrease. After a little practice the operator can place a renovator equipped with one of these swivels in almost any position without inconvenience. Illustrations of the possibilities of this form of swivel are presented inFigs. 39and40, in which an operator is shown cleaning the treads and risers of a stairway without changing her position, and inFig. 41, where the operator is cleaning the trim of a door with apparent ease. The author considers that this form of swivel is the only satisfactory joint between the renovator and its stem. It is being rapidly adopted by nearly every manufacturer of vacuum cleaners.

FIG. 38. SWIVEL JOINT ARRANGED TO PREVENT DUST LODGING BETWEEN THE WEARING SURFACES.

In operating any renovator it is nearly always drawn backwards and forwards in front of the operator, across the surface to be cleaned. When the hose is rigidly attached to the upper end of the stem, it becomes necessary to drag at least a portion of the cleaning hose along with the renovator when it is moved forward, and to crowd the same back on itself when the renovator is moved backward. This action has a tendency to kink or snarl the hose about itself and makes the operation of the renovator very awkward, often causing the operator’s feet to become entangled in the hose.

FIG. 39. SWIVEL JOINT IN USE.

This action also brings an undue amount of wear on the hose near the end which is attached to the stem, as may be readily noted by inspection of hose used with rigidly-attached stems. This will show that the end of the hose is entirely worn through, while the remainder of the hose is still in serviceable condition.

The trouble above stated can be overcome by providing a swivel joint at the point of connection between the hose andthe stem. A few attempts to use a joint similar to that first described in connection with the renovator and its stem, as illustrated inFig. 37, have been made, but without much success, as the bolt through the air passage catches dirt and there is not sufficient freedom of movement between the portions of the swivel. Variations of this form of joint have been made, one of which is provided with a screwed union to join the two portions, as shown inFig. 42. This is a much better form than that first described and has been successfully used in connection with heavy 1-in. diameter hose. Care must be exercised that the direction of the flow of air is always in the direction indicated by the arrows in the sketches, as a reversal, if only for a short time, will ruin the joint, due to lodgment of dust in the moving parts.

FIG. 40. ANOTHER USE OF SWIVEL JOINT, SHOWING POSSIBILITIES OF THIS FORM.

Still another variation in this form of swivel has the two main parts made to fit one within the other and a snap ring isplaced in a groove in the male portion of the joint, this groove being deep enough to take the entire thickness of the ring. The two parts are then fitted together and the ring snaps out into a corresponding groove in the female portion of the joint, uniting the two parts. This joint gives a fairly free movement to the parts thereof, but has the disadvantage that it cannot be taken apart without breaking one of its parts.

FIG. 41. OPERATOR CLEANING TRIM OF DOOR WITH SWIVEL JOINT.

FIG. 42. SWIVEL JOINT, WITH SCREWED UNION.FIG. 43. SWIVEL JOINT HAVING BALL BEARINGS.

FIG. 42. SWIVEL JOINT, WITH SCREWED UNION.

FIG. 43. SWIVEL JOINT HAVING BALL BEARINGS.

A modification of this form of swivel has been made by the manufacturers of the last-described swivel, in which semi-circular grooves have been cut, one on the inside of the femaleportion and one on the outside of the male portion. Steel balls are forced into this groove, after the parts are assembled, through an opening provided in the edges of the parts. This opening is closed, after the balls are in place, by a small pin, as shown inFig. 43. The swivel then becomes a ball-bearing joint, with a freedom of motion characteristic of such bearings. This joint readily responds to every movement of the stem and keeps the hose hanging vertically downward and always free from kinks. Its action is illustrated inFig. 44, in which it is being used in connection with a carpet renovator. This joint is considered to be the most efficient on the market. It is protected by a patent controlled by a manufacturer of vacuum cleaners.

FIG. 44. ACTION OF BALL-BEARING SWIVEL JOINT.

Valves are placed at the upper end of the stems by many manufacturers, to cut off the suction when carrying the renovators from room to room, and when it is necessary to stop sweeping to move furniture. These valves have nearly always taken the form of a plug cock with tee or knurled handle. They are useful on large installations, where vacuum control is either inherent in the exhauster or where some means of vacuum control is provided, as a considerable saving of power may be obtained by closing same, as will be explained in a later chapter, and to overcome the unpleasant hissing noise caused by the inrush of air into the renovator when same is held off the floor.

FIG. 45. ILLUSTRATION OF DEFECTS OF PLUG COCKS.

When the exhauster has a capacity of but one sweeper and when the cleaning is done at times when the building is unoccupied, there seems to be little need for this refinement, which has two defects: first, the operators will not close the valves: second, when they have been closed they are only partly opened, as indicated inFig. 45. When this occurs, the portions of the plug, which are shown stippled, are quickly cut away by the sand-blast action of the dust, making it necessary to open the valve a still smaller amount the next time it is operated, cutting off still more of the plug until a new plug is necessary in order to make the valve again operative.

A few attempts have been made to overcome these defects by making the valves self-closing and having them so constructed that when the operator grasps the handle the valve will be forced wide open, on the principle of the pistol grip. These valves will, of course, close whenever the handle is released, and it is impossible to grasp the handle in any degreeof comfort without throwing the valve wide open. However, since the valve is closed by a spring, considerable pressure must be applied to the handle in order to keep it open and it acts similar to the Sandow dumb bell in producing fatigue of the fingers in a short time; they have not come into general use. The use of valves in the renovator handle is considered by the author to be an expense not justified by the gain in economy and they are no longer included in specifications prepared by him.

Back to Index Next