US3496899A

US3496899A - Pneumatic trim device

Info

Publication number: US3496899A
Application number: US729612A
Authority: US
Inventors: Milton N Weber
Original assignee: MILTON N WEBER
Current assignee: MILTON N WEBER
Priority date: 1968-05-16
Filing date: 1968-05-16
Publication date: 1970-02-24
Anticipated expiration: 1987-02-24

Description

Feb. 24, 1970 -M. N. WEBER PNEUMATIC TRIM DEVICE 4 Sheets-Sheet 1 Filed May 16, 1968 INVENTOR. fit/20:2 Z l Veer TURN E KS Feb. 24, 1970 M. N. WEBER 3,496,899

I'm-mum TRIM nmvxcn Filed May 16, 1968 4 Sheets-Sheet VACUU M SOURCE INVENTOR.

ray 75 22 J k grs Feb. 24, 1970 M. N. WEBER rnnummmmm DEVICE 4 Sheets-Sheet :3

Filed May is, 1968 INVENTOR. 275212022 27. Weer BY M M. N. WEBER rummmmic TRIM DEVICE Feb. 24, 1970 Filed May 16 1968 4 Sheets-Sheet 4 T TO/QNEYS United States Patent 3,496,899 PNEUMATIC TRIM DEVICE Milton N. Weber, 20655 Audette,

Dearborn, Mich. 48124 Filed May 16, 1968, Ser. No. 729,612 Int. Cl. B63b 1/18, 1/32 US. Cl. 11466.5 20 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to trim devices for boats and, more particularly, to a trim tab actuated by fluid pressure.

A well known problem encountered when operating a power boat with the means for propulsion at the rear, is a change in attitude of the boat as power is increased. This change in attitude more specifically involves a raising of the bow out of the water and a lowering of the stern into the water. This high bow attitude increases the profile drag, for example the depth to which the boat extends into the water. This increased drag has an adverse effect on the fuel usage as well as tending to slow the boat down for a given power setting. It is, therefore, desirable to provide means on a boat for correcting the tendency of the boat to ride stern low in the water and bring the boat into a condition where it will plane. When a boat planes, the pointed portion of the bow is knifing through the water, and the boat has a maximum amount of free board, that is, more of the sides of the hull of the boat ride out of the water than in the water. Under these conditions the least amount of the hull surface is in contact with the Water thereby minimizing the drag and increasing the boats performance.

The prior art shows many devices for bringing a boat into a condition of plane, but there are various disadvantages associated with each. For example, the prior art shows planing surfaces or trim tabs that can be positioned downwardly of the hull of a boat at an angle with respect thereto to cause the bull to lift out of the water to bring about the desired planing condition. One common form of this type of trim plane is a mechanically set unit that is adjusted before a boat is underway and is pre-set at an angle which it is expected will be most efficient in bringing the boat into plane when operated. Of course, the exact operating conditions of a boat are difficult to predict and, in fact, will change as the boat is underway, for example due to fuel consumption. For this reason the setting of these mechanical devices is a compromise between the boat having a given weight distribution and an expected weight distribution, while also being restricted to making the boat plane only under a given speed condition. When any of these predicted values change, the planing devices are ineffective and, in fact, can become detrimental to the performance of the boat. Therefore, such devices have not found wide usage.

Another form of trim device found in the prior art involves a deflectable trim plane that is actuated by mechanical means such as by a jackscrew. The jackscrew can be either manually operated, or in some installations is power driven, as by an electric motor. In this manner,

3,496,899 Patented Feb. 24, 1970 "ice the aforementioned shortcoming of the fixed mechanical device is overcome in that the angle of the planing surface can be adjusted while the boat is underway thereby compensating for changes in operating conditions. These devices have shortcomings in that, during installation, there must be multiple holes made in the hull of the boat which are subject to leakage in order to bring the device into engagement with the trim tab. In addition, there is a great deal of involved apparatus which necessarily increases the expense, and these complex mechanical controls are subject to malfunction and corrosion. A further complication of a mechanically operated remote control trim tab is that if the trim tab is struck by an obstacle in the water, damage necessarily results due to the nonresilient nature thereof. This type of device has come into wider usage than the aforementioned fixed device, but is yet limited only to the more expensive boats wherein the great expense of a remote control mechanically operated trim tab can be justified. Therefore, most boats constructed today are not provided with this type of trim tab.

Still another kind of trim tab found in the prior art is the type where an attempt is made to provide a fluid operated trim tab that provides an easy mode for remote control and which provides a resilient surface so that if a foreign object in the water is struck by the tab, very little damage ensues. However, there are certain disadvantages associated with the pneumatically operated trim tab shown in the prior art. For example, a fluid operated trim tab can very readily deflect a planing surface into the path of water passing the boats hull, but means normally must be provided for the return of the trim tab to a position of rest when the trim is to be changed to a lower setting or when trim is to be dispensed with. Therefore, springs or some other type device are connected to the end of the tab to provide this return action, and this return device necessarily involves another item subject to corrosion and malfunction. In addition, when the fluid operating device takes the form of a cylinder, there is great expense involved and again the installation is rather complex to carry out. In addition, a cylinder has metallic parts which are subjected to the corrosive elements associated with a boats environment, and a serious maintenance problem exists relative thereto. For this reason, a cylinder type fluid device for operating trim tabs has not found wide usage on boats. 7

When the type of fluid operated trim tabs found in the prior art which involve inflatable bags are used, another problem presents itself. The inflatable bags shown in the art are resilient members that, when expanded, tend to assume a round shape. This is the natural tendency of an inner tube type of resilient bag. The prior art does not show means for restraining the inflation of certain areas of these bags so that they will assume a desired shape which is compatible with a deflectable trim tab. In addition, the fluid operated trim tabs of the prior art are mainly adapted for mounting on the transom of a boat because of their thickness which would dictate, if they were mounted on the bottom of the hull of the boat, that they would provide suflicient drag under certain operating conditions to offset the advantages that they would provide under other more favorable operating conditions. If recesses in the hull of the boat are provided for such devices, as shown in the prior art to accommodate their thickness, an add-on version of the trim tab is precluded and the trim tab can be installed on a boat only as original equipment. This seriously limits the market for such devices.

Fluid operated trim tabs of the prior art that use inflatable bags are either unrestrained and, therefore, tend to ballon or present too much volume for expansion initially so that the response of the device is rather slow.

In addition, if a hand pump or bulb were used, the volume of air required to inflate the bag would be excessive and, therefore, time consuming.

The present invention contemplates the solution to the aforementioned problems by providing a device for craft of the type which moves through a fluid comprising trim means adapted for attachment to the craft and including a planing member having first and second extremities with the first extremity pivotal about a position adjacent the second extremity. An inflatable means is provided which coacts with the planing member for pivoting the planing member while being inflated, the inflatable means having an increasing available volume in a direction toward the second extremity from a position adjacent the first extremity. Preferably the inflatable means is inelastic and, when inflated defines cross sectional areas in successive parallel planes transverse to the direction of the second extremity and increases in cross section going toward that direction. In this manner, a bag made of some inelastic material can lay approximately fiat between a planing member and hull of a boat and is of generally triangular shape in an uninflated condition. The bag generally defines an elongated isosceles triangle with the base of the triangle being attached between the trim plate and the hull. The tip of the isosceles triangle shaped bag extends along the length of the trim plate which is of an inherently resilient material. Therefore, when inflation of the bag commences, the tip of the trim plate offers the least resistance to inflation so the tip of the bag inflates first deflecting the tip of the trim plane away from its position of rest. As more air is pumped into the bag, the bag progressively fills from the tip toward the base of the isosceles triangle shaped portion. The bag being inelastic, when the bag fills to its inflated shape, a wedging action is generated going toward the connection of the trim plate to the hull and causes further deflection of the plate. As this occurs, the volume of the bag increases so that there is greater bearing surface acting against the plate so that practically every bit of inflation is translated into deflection of the plate. Due to the relatively small volume of the bag, the movement of the trim plate in a deflecting manner is very quick. It should also be noted that as the bag is inflated, starting at the angle opposite the base of the isosceles triangle, inflated portion of the bag draws out of engagement with the trim plate and the hull of the boat, and only the uninflated portion, or partially inflated portion, continues in engagement with the hull or trim plate. Therefore, the bag essentially retains its triangularity in a plane essentially parallel to the boats hull and assumes a triangularity in a plane perpendicular thereto.

The bag and planing member can be secured beneath a boarding step projecting to the rear of the transom of the boat if desired. The entire assembly is sufliciently thin so that the bag and planing member can be disposed in a depression in the boats hull or mounted on the hulls surface as desired. The bag is generally composed of a nylon reinforced plastic material of sheet form with the sheet being folded and heat fused into an enclosurure. In one embodiment the bag is inflated by a hand bulb located near an operating station. In another embodiment, the bag is inflated by a vacuum driven pump regulated by a control at an operating station.

In another embodiment, the bag has a rigidifying member disposed inside to insure a desired inflated bag configuration, and the bag is secured to the hull of the boat on a line substantially along the length of the bag and on a line along the Width thereof at an end. The bag is inflatable by fluid pressure to form a planing surface for the boat that is angularly disposed with respect to the boats hull with the surface of the bag being the actual planing surface. In this embodiment, the bag returns to a position adjacent the boats hull when pressure is relieved therein by the natural resilience of the bags material. This bag is also adaptable to be carried on an extension from the boats transom such as under a boarding step. 1

Accordingly, it is an object of the present invention to provide an improved trim device for a boat that includes a planing member pivotal about a first extremity and deflectable away from a boats hull by the inflatable means coacting with the planing member for pivoting the planingmember, the inflatable means having an increasing available volume for expansion in a direction going from the free end of the planing member to the first extremity.

It is another object of the present invention to provide an improved trim device, as set forth in the previous object, wherein the inflatable means is inelastic.

It is still another object of the present invention to provide an improved trim device for a boat wherein a deflectable trim plane is extended by inflating a bag that is generally the shape of an isosceles triangle and is secured to the boat along the base portion of the triangular shape so that when inflated, the bag essentially retains its triangularity in a plane parallel to the boats hull and assumes a triangularity in a plane perpendicular thereto.

It is yet a further object of the present invention to provide an improved trim device as set forth in the previous objects wherein the inflatable means, when inflated, dcfines cross sectional areas in successive parallel planes transverse to a line running from the free end of the planing members toward the first extremity.

It is a further object of the present invention to provide an improved trim device for a boat wherein a deflectable plane is moved by a bag having a fluid pressure generated therein by a hand bulb located near an operating station.

It is yet a further object of the presnet invention to provide an improved trim device for a boat wherein a bag is attached to the hull of the boat and has a rigidifying member disposed inside which restrains the bag against free inflation and forms an aerodynamic shaped enclosure beneath the hull of the boat that acts as a trim plane.

Other objects and intended advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIGURE 1 is an elevational view of a boat with parts broken away showing the subject invention in its operative environment.

FIGURE 2 is an elevational view of the transom of a boat with the subject trim plane shown in a deflected condition.

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2.

FIGURE 4 is a diagrammatic illustration of a poweroperated trim plane arrangement in accordance with the present invention.

FIGURE 5 is a sectional view similar to the view in FIGURE 3 but with the trim plane in deflected condition.

FIGURE 6 is a perspective view with parts broken away of the inflatable bag of the subject invention.

FIGURE 7 is a diagrammatic illustration of a manual fluid pressure producing means for the subject invention.

FIGURE 8 is a view, partly in section, taken along line 8-8 of FIGURE 7.

FIGURE 9 is a sectional view taken along line 99 of FIGURE 10.

FIGURE 10 is a sectional view of another embodiment of the present invention shown in a position of rest.

FIGURE 11 is a sectional view of the embodiment of FIGURE 10 with the trim plane shown in deflected condition.

FIGURE 12 is a sectional view of another modification of the present invention shown mounted under a boarding step suspended from the transom of a boat.

FIGURE 13 is another modification of the present invention shown attached to the transom of the boat but mounted beneath the hull thereof.

Referring to FIGURE 1, a boat generally designated by numeral is illustrated with trim tabs 12 shown mounted on hull 14 thereof in a deflected condition brought about by inflation of bag 16. Air line 18 supplies fluid under pressure that is regulated by valve assembly 20 mounted near the operating station of the boat 10.

FIGURE 2 is an enlarged view of the boat of FIG- URE 1 showing trim tabs 12 in a deflected position as viewed from behind the transom of boat 10.

Referring to FIGURE 3, one means of mounting the trim tabs on the boat is shown wherein the whole assembly is contained within recess 22 formed in hull 14. It is understood that a surface mounting on the hull is also desirable due to the thinness of the device. Trim tab 12 is composed of a resilient material, such as stainless steel and is substantially a continuation of hull 14 so as to provide a relatively smooth outer surface for the hull in the area where the trim tab is located. Trim tab or planing member 12 is shown as a relatively flat rectangular member, but it is understood that the size, shape or thickness of the tab 12 can be suited to a particular operative environment. In addition, it might be desirable when mounting the tab on a severely contoured area of a hull to have the tab contoured in a complementary manner so that a clean profile is provided for the hull or so that an aerodynamic shape is generated for specific desired conditions of lift. Recess 22 is sufliciently deep so that when the planing surface of trim tab 12 is operably mounted, bag 16 is compressed between trim tab 12 and the base of recess 22. An aperture is provided through the hull for the reception of tubular element 24 which is bonded in any well known manner to bag 16. The free end of tab 12 is termed a first extremity, and screws 26 pass through trim tab 12 and bag 16 prior to being threaded into the body of hull 14 near a second extremity of tab 12.

Referring to FIGURE 5, bag 16 is shown in expanded disposition with resilient trim tab 12 shown in a deflected condition. It is noted in FIGURE 5 that bag 16 has a substantially triangular shape up to point 26 in a perpendicular manner with respect to hull 14. The flat plate area of trim tab 12 up to point 26 is sufiicient to cause the lift to hull 14 that is desired. The outer portion, or extension, of trim tab 12 extending beyond point 26 is free to deflect and can easily be deflected toward hull 14 if a foreign object is struck by the tab as the boat is moving through the water. If the impact is sufliciently great, bag 16 will be distorted against hull 14 thereby further cushioning the shock to trim tab 12. When pressure is relieved in bag 16, resilient trim tab will move back to the position as shown in FIGURE 3 due to its own inherent resilience.

Referring to FIGURE 6, the bag 16 is shown as being generally the shape of an isosceles triangle and having holes 30 passing therethrough, adapting the reception of screws 26. The tip is adjacent the first extremity of the tab 12, and the base of the triangle is adjacent the second extremity of tab 12. This is the base portion of the triangular shape so that when inflated the bag will essentially retain its triangularity in a plane parallel to the boats hull and, as seen in FIGURE 6 and in FIGURE 5 will assume a triangularity in a shape perpendicular to the boats hull. The bag 16, when inflated, defines crosssectional areas that increase in size when measured from the first extremity of tab 12 toward the second extremity thereby near its anchor point. When a point near element 24 is reached, continuing toward the anchor point, the cross-sectional areas diminish. Therefore, the bag is constrained between tab 12 and the boats hull. The tab 12 is resilient, and it is noted that it takes less force at the free end to deflect tab 12 than at any other point nearer its anchor point. Near this end the bag is pointed and has the least volume. Therefore, when inflation starts, the tip, being less constrained than other portions of the bag, fully inflates first with the bag progressively filling toward its largest cross-sectional area or volume. In other words, the inflated cross-sectional area in successive parallel planes going from the tip of the isosceles triangle shape toward the base increases as the bag is filled up to a certain point and then decreases as the second extremity of tab 12 is approached by a completely inflated volume of the bag. The bag is inelastic and as a part fills, it becomes free of the hull and tab 12, and all further air input goes toward bringing about further deflection of tab 12 and filling of the unfilled volume in bag 16. In this manner, the bag provides the amount of support to the trim tab 12 in the area of deflection to maintain a set angularity when in an inflated condition. The bag is composed of a reinforced plastic material that is originally in sheet form and then is folded as at 32 and heat fused into an enclosure. Element 24 is likewise fused onto bag 16 in any well known manner, such as by electric welding. Bonding is also acceptable in certain installations.

Referring to FIGURE 7, valve assembly 20 is shown, and has a pressure input through fitting 32. In the embodiment of FIGURE 7, fitting 32 communicates pressure from bulb 34 which is more clearly shown in FIG- URE 8.

Referring to FIGURE 8, a check valve assembly 36 is illustrated so that when pressure is generated by squeezing bulb 34, an increase of pressure is registered in manifold 38, and this pressure is trapped therein. Manifold 38 communicates with a pair of trim tab arrangements through

lines

40 and 42 respectively. Valve assembly 20 is of a common construction that allows

lines

40 and 42 to be separately controlled by

knobs

44 and 46 respectively. Dump buttons 48 and 50 are disposed in the center of

knobs

44 and 46 respectively so that it is possible to separately regulate the pressure in the pair of trim devices so that an imbalance therein can be created to offset a load shift in the boat.

Referring to FIGURE 4, a very similar arrangement is shown wherein a vacuum pump 52 is substituted for the bulb assembly 34 and is of the type that is operated through line 54 communicating with a vacuum source such as the intake manifold of an internal combustion engine. Outlet 56 of pump 52 communicates with fitting 32 in much the same manner as bulb 34. Pump 52 is a well known type such as the pumps manufactured by the Hadley Manufacturing Company of Toledo, Ohio, and is utilized as an air pressure control for load level ing mechanisms of station wagons. Pump 52 will pressurized line 58 and manifold 38 with air pressure selectively routed to

lines

40 and 42 as desired. Valvr: assembly 20 is so designed that a selective pressure dump can be effected through dumping ports not shown, or pump 52 can be controlled through a solenoid operated valve assembly likewise not shown. The manner of controlling pump 52 is not considered to be a portion of the present invention and can be affected in any way suitable in a particular installation as determined by Y the designer of the system.

Referring to FIGURE 10, another embodiment of the subject invention is illustrated in which a reaction member 60 is carried within bag 16, with bag 16 being bonded to the base of recess 22, preferably up as far as point 62, as seen in FIGURE 11. Bag 16 in this environment is of a plastic material having a slight amount of elasticity, which elasticity provides the return means for the planing member herein shown when pressure is relieved from bag 16. It is noted that reaction member 60 is a rigidifying member and tends to control the lateral shape of bag 16 when inflated. Bag 16 can take any shape therefore in this embodiment in view of the fact that its outer dimension is controlled, and it is prevented from going into a generally circular bag when inflated. As seen in FIGURE ll, the generally triangular vertical shape is also maintained up to approximately point 64 which is equivalent to point 28 as shown in the embodiment of FIGURE 5. Therefore, the same effective planing area is presented to the water passing hull 14 as in the previous embodiment with the same resistance to shock from striking a submerged object that is available in the embodiment of FIGURE 5. FIGURE 11 has the added advantage of presenting an aerodynamic shape so that the water flow thereby is considerably smoother than in the planing members shown in the prior art. It should also be pointed out that both the embodiment of FIGURE and embodiment of FIGURE 11 provides the device with an adjustability heretofore unknown. That is, when a planing member is deflected a given amount to bring about a performance desired at a given speed, and the speed is increased without changing the planing member, the force of the water rushing against the planing member will tend to depress it thereby automatically regulating the trim a limited amount which can be an important feature when slight variations in speed are undertaken which are insuflicient to warrant the changing of the trim. It should also be noted that, whereas in both the embodiments of FIG- URE 5 and FIGURE 11 the trim arrangements are shown as mounted in recess 22, they are sufficiently thin in cross section, when retracted, to be mounted on the outside of the hull of the boat so as to adapt the subject device to be available as an after-market installation if they were not originally installed in the boat when sold.

Also available for after-market installation is the embodiment of FIGURE 12. The same device shown in FIGURE 5 is illustrated in this embodiment which is mounted under boarding step 66. This, of course, is a much. easier mode of installation that, in the case of small boats, can be readily made when the boat is pulled from the water. The embodiment of FIGURE 13 is very similar in that the boarding step concept is also used, but bracket 68 can be bolted to the transom 70 of boat without moving the boat from the water, yet allowing the trim plane device to be situated on the base of hull 14. Both the embodiments of FIGURES 12 or 13 are particularly adaptable for use on small boats such as those used for water skiing.

The various embodiments shown in the subject device tend to illustrate more clearly the versatility of the device in that it can be used for original equipment manufacture or can be used in the after-market for add-on to an existing boat. In addition, the device is adapted to be multiply mounted, that is in pairs or groups larger than pairs on either side of a boat of a greater length than is practical to control with only the pair mounted as shown in FIGURE 2. To explain further, a boat in cess of 30 feet, for example, might req-uirethe flat plate area that is presented by a pair of trim tabs on either side of the hull. In addition, due to the location of the propellers on certain boats, that is dual engine boats, it may be important to locate a trim tab on either side of the water flow into the propellers to prevent cavitation. In still other installations, depending upon the weight distribution within the boat, it might be appropriate to mount trim tabs further toward the bow of he boat than shown in the illustrations in the drawings. Of course, the exact position of the mounting of the trim tabs is left to the particular artisan involved in the installation, for all boats have different weight distributions and are oriented toward operation at different speeds which might change the most desirable point on the hull of the boat for locating the trim tabs.

Another feature extending the utility of subject devices is that the mounting of the trim tabs of the subject invention involves only making one hole in the hull of the boat that must be sealed. This is the hole through which element 24 extends. The remaining part of the installation is made very simply by screws into the hull of the boat, whether the trim tab arrangement is situated in a recess, such as shown at 22, or on the surface of the hull which would be the normal installation point when added on to the boat after construction thereof.

The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of Words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention can be practiced otherwise than as specifically described.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A device for a craft of the type which moves through a fluid comprising: trim means adapted for attachment to the craft and including a planing member having first and second extremities with the first extremity pivotal about a position adjacent the second extremity; and inflatable means coacting with said planing member for pivoting said planing member while being inflated; said inflatable means having an increasing available volume in a direction toward said second extremity from a position adjacent said first extremity.

2. A device as set forth in claim 1 wherein said inflatable means is inelastic.

3. A device as set forth in claim 2 wherein said inflatable means, when inflated, defines cross-sectional areas in successive parallel planes transverse to said direc tion which increase in said direction.

4. A device as set forth in claim 3 wherein said cross sectional areas in said successive planes increase to a maximum and thereafter decrease in said direction to said second extremity.

5. A device as set forth in claim 4 wherein said inflatable means comprises a bag which when inflated and viewed in side elevation diverges from a position adjacent said first extremity toward said second extremity and then converges the remainder of the distance to a position adjacent said second extremity.

6. A device as set forth in claim 5 wherein said bag has a generally triangular configuration when viewed in plane with opposite diverging sides and a base, said base being disposed adjacent said second extremity.

7. A device as set forth in claim 6 wherein said bag is disposed adjacent said planing member whereby the bag may react between the planing member and the craft.

8. A device as set forth in claim 7 wherein said planing member is yieldable and has memory.

9. A device as set forth in claim 8 wherein said planing member comprise spring steel.

10. A device as set forth in claim 9 wherein said plane member is rectangular.

11. A device as set forth in claim 8 including fluid pressure means in communication with said bag for inflating said bag.

12. A device as set forth in claim 5 wherein said planing member is disposed within said bag.

13. A device as set forth in claim 12 wherein said planing member is rectangular.

14. A device as set forth in claim 12 including fluid pressure means in communication with said bag for inflating said bag.

15. A device as set forth in claim 8 wherein said bag comprises a reinforced plastic material.

16. A device for a craft of the type which moves through a fluid comprising: trim means adapted for attachment to the craft and including a planing member having first and second extremities with the first extremity pivotal about a position adjacent the second extremity, and inflatable means adapted to react between said planing member and the craft and adapted to contact the craft along the length thereof when deflated and for successively moving out of contact with the craft therealong only in a direction from said first extremity toward said second extremity as said inflatable means is inflated.

17. A device as set forth in claim 16 wherein said inflatable means is inelastic.

18. A device for a craft of the type which moves through a fluid comprising: trim means adapted for attachment to the craft and including a planing member having first and second extremities with the first extremity pivotal about a position adjacent the second extremity, and inelastic inflatable means adapted to react between said planing member and the craft and adapted to contact the craft along the length thereof when deflated and for successively moving out of contact with the craft therealong in a direction from said first extremity toward said second extremity as said inflatable means is inflated, said inflatable means, When inflated, defining crosssectional areas in successive parallel planes transverse to said direction which increase in said direction.

19. A device as set forth in claim 18 wherein said cross sectional areas in said successive planes increase to a maximum and thereafter decrease in said direction to said second extremity.

20. A device as set forth in claim 19 wherein said inflatable means comprises a bag which when inflated and viewed in side elevation, diverges from a position adjacent said first extremity toward said second extremity and then converges the remainder of the distance to a position adjacent said second extremity.

References Cited UNITED STATES PATENTS 3,313,262 4/1967 Yunker et a1. 11466.5

ANDREW H. FARRELL, Primary Examiner