Multi-directional type parallel rule

Abstract

 A multi-directional parallel rule 1 for e.g. navigational plotting or draughting comprises an edge 3 of a selected shape, e.g. straight, and a first pair of spaced apart wheels 6 mounted to enable the edge 3 to be moved in a first direction. A second pair of wheels 10 are mounted to enable the edge 3 to be moved in a second direction 18 substantially at right angles to the first direction.

Description

[0001] This invention relates to a rule particularly a multi-directional type parallel rule.

[0002] The two types of parallel rules presently in common use are the stepping type and the one way roller type.

[0003] In particular for navigational plotting stepping type parallel rules are not always satisfactory as they require both hands to operate. The movement of a boat can be such that it is often desirable to hold oneself steady with one hand while plotting a course or drawing a position.

[0004] Present types of roller parallel rules move in one direction only, namely forward and backwards, therefore the area covered is limited to the length of the rule unless it is lifted off the paper and reset for another area.

[0005] Neither stepping type or one way roller type parallel rules can perform all the functions normally required in line drawing or chart plotting without the use of other instruments such as set squares, protractors and dividers and in the case of chart plotting, mathematical calculations to allow for compass variation and magnetic deviation.

[0006] As such existing parallel rules are disadvantageous.

[0007] It is therefore an object of the present invention to provide a rule which will obviate or minimize the foregoing disadvantages in a simple yet effective manner or which will at least provide the public with a useful choice.

[0008] Accordingly the invention consists in a rule comprising a straight edge or edge shaped to a selected shape, a first pair of spaced apart wheels, mounted to enable said edge to be moved in a first direction and a second pair of wheels mounted to enable said edge to be moved in a second direction substantially at right angles to said first direction.

[0009] This invention may also broadly be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

[0010] The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

[0011] One preferred form of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a plan view of a rule according to one preferred form of the invention; and

Figure 2 is an end view of the rule of Figure 1.

[0012] Referring to the drawings a rule 1 is provided which in the preferred form has a plate 2 which provides a desirably shaped edge and in particular straight edge 3. Two pairs of spaced apart wheels are mounted in the plate and in the preferred construction a housing 4 is provided with a pair of dividing walls 5 spaced inwardly from the end walls 7 of the housing. Between the dividing walls 5 are provided a pair of spaced apart first wheels or rollers 8 which may be mounted on an axle 8 the ends 9 of which may be engaged with apertures in the walls 5. A keyhole type aperture extending from the bottom edge of the wall 5 may be provided into which the axle ends 8 may be snapped. In the preferred construction the wheels or rollers 6 have some width for example about 1cm and are provided with a knurled finish preferably being formed of metal such as copper or brass.

[0013] A pair of second wheels 10 are provided and these again may be about 1cm in width with a knurled finish being formed in metal and these are provided so that there axis of rotation is substantially at right angles to the axis of rotation of the wheel 6. The wheels 10 may be provided on axles 11 which may snap into keyhole apertures in the front wall 12 and rear wall 13 of the housing 4.

[0014] The wheels 6 are set so that the bottom parts 15 of the wheels extend below the plate 2 thus the plate 2 can rock a little on the axle of the wheel 6. The wheels 10 are positioned so that with the straight edge 3 resting on the surface 16 the lower part 15 of the wheel 6 will be in contact with the surface 16 but the wheel 10 will be free of that surface. However the position of the axle 11 in the rear wall 13 is desirably higher in use than the position of the axle 11 in the front wall 12.

[0015] Thus the lower surface 16 of the wheel 10 is at an angle to the plate 2 as can be clearly seen in Figure 2. Thus in use if the wheel is rocked about the wheel 6 until the wheel 10 comes into contact with the surface 16 a further continuation of that motion will cause the lower part 17 of the wheels 10 to come into contact with the surface allowing the lower part 15 of the wheel 6 to be lifted from the surface as can be seen in Figure 2.

[0016] The included angle between the plane of the plate 2 and the plane of the lower surface of the wheels 10 is desirably quite small and about 5 degrees has been found suitable.

[0017] In that position the ruler can be moved in the direction of arrow 18 shown in Figure 1. When rocked onto the wheel 6 movement of the rule in a direction at right angles to the arrow 18 is possible.

[0018] The plate 2 can be marked with any suitable markings for example for navigational purposes, draughting purposes or otherwise.

[0019] In the preferred form of the invention a pivoting arm 20 is provided and this can be attached to a flexible dome 21 for example moulded into a plate 2 desirably formed of a plastics material. Thus the arm 20 has an aperture 22 at one end thereof that may be snapped onto the dome as the diameter at the base of the dome is smaller than the diameter at the top as can be seen from Figure 2. The walls of the aperture 22 may be similarly sloped. The dome 21 is made in several segments so that each segment can flex and cause the top of the segment to bend inwards therefore reducing the diameter of the segmented circle when the arm 20 is pulled off the dome 21 to be placed on a further dome 22 at the other end of the construction. The fit between the domes 21 and 23 are sufficiently tight so that friction will keep the arm 22 at whatever angle it is set to during use.

[0020] For measuring distances between two position for navigation purposes the arm 20 and the ruler edge 3 are marked with small arrow heads 24 and 25 and the arm 20 can be adjusted so that the arrow heads 24 and 25 will span over the distance to be measured. The distance is then matched against the latitudes scale on the chart to obtain naughtical miles thereby eliminating the need for separate dividers. the pivoting arm 20 can be placed on either dome 21 or 23 to suit west or east variation and the degree set at the sum of compass variation and magnetic deviation to obtain true course, along the ruler edge 3 and compass course along the pivoting arm edge 26 which eliminates or reduces the need for further mathematical calculations.

[0021] The use of the invention is as follows.

[0022] In use the ruler can be moved in a direction substantiate at right angles to the direction of the edge 3 by pivoting the construction so that the bottom part 15 of the wheel 6 engage the surface 16.

[0023] Movement in the direction parallel to the edge 3 can be achieved by rocking the construction back to the position shown in Figure 2 so that bottom 16 of the wheel 10 engages the surface 16.

[0024] Thus it can be seen that at least in the preferred form of the invention a rule is provided which has the advantage that movement in two directions can be achieved with a single hand and without the need to lift the rule from the page. This is desirable both for draughting and navigational plotting purposes and is particularly useful for navigational plotting purposes where the free hand can be used to hold a person steady whilst plotting a course or drawing a position.

Claims

1. A rule comprising a straight edge or edge shaped to a selected shape, a first pair of spaced apart wheels, mounted to enable said edge to be moved in a first direction and a second pair of wheels mounted to enable edge edge to be moved in a second direction substantially at right angles to said first direction.

2. A rule as claimed in claim 1 wherein said wheels have a knurled surface.

3. A rule as claimed in either claim 1 or claim 2 wherein said edge is the edge of a plate and said wheels extend below the level of said plate being positioned so that said rule may be moved between positions wherein a selected pair of wheels contact a surface on which said rule is moved.

4. A rule as claimed in claim 3 wherein said second pair of wheels have an axis of rotation making a relatively small included angle with the plane of said plate.

5. A rule as claimed in claim 4 wherein said included angled is about 5 degrees.

6. A rule claimed as in any one of claims 3 to 5 that has a removable pivoting arm.

7. A rule as claimed in claim 6 including flexible domes moulded into said plate at each end in the form of protruding segmented circles, said arm having an aperture therein enabling said arm to be engaged onto a selected one of said domes.

8. A rule as claimed in either claims 6 or claim 7 that has arrow markings on the ruling edge and edge of the removable pivoting.

Drawing