AU671362B2 - Polymeric hatch cover - Google Patents

Description

AUSTRALIA

Patent Act COMPLETE SPECIFICATI ON

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: oo oo Names(s) of Applicant(s): NYLEX ROTOMOULD PTY. LTD.

Actual Inventor(s): o ROBERT WATTS IAN WALTON Our Address for Service is: PHTLLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne, Australia, 3000 Complete Specification for the invention entitled:- POLYMERIC HATCH COVER The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 1 I -r III

I

2 POLYMERIC HATCH COVER The present invention relates to hatch covers more particularly it relates to hatch covers for cars or carriages for bulk transportation of flowable particulate goods such as grain. It will be convenient to describe the invention with particular reference to use in relation to railway grain hopper cars although it should be noted that the invention has a wider application.

An important aspect of railway hopper cars used for transportation of particulate goods such as grain is the ease with which the car can be filled and emptied. The features of the hatch cover are important for the loading of the car and can determine the ease and rate at which the car can be loaded. Clearly the easier it is to gain access to the car hopper the faster a car can be loaded.

Delays or inconvenience experienced in loading of a car due to faulty operation of the hatch covers can result in increased maintenance costs and loading costs and thus e reduced profitability.

Hatch covers are preferably designed so that part or all of the car hatch opening can be opened and goods loaded into the hopper. It is desirable that each hatch cover functions reliably and is capable of repeated •opening and closing without deformation and are desirably resistant to the usual stresses and vibrations exerted on railway transport vehicles. Moreover, as workers are required to walk over the hatch covers during filling operations it is important that the covers be of suitable strength to support the weight of such workers and be able to withstand relatively heavy foot-traffic from workers.

JL 0477i I ~C 3 Known types of hatch covers presently in use are generally manufactured from sheet steel. Such covers have been used for many years and are the most common type of hatch covers. While such covers may be satisfactory ear'.y in their life, after years of constant vibration and exposure to sun and rain experience has shown that steel covers may fail due to fatigue of the steel. Furthermore, such covers must be constantly adequately protected from corrosion and must be maintained in good condition to prevent contamination of the hopper contents from rust, flaking paint and the like. Other problems associated with steel hatch covers is that they can be heavy for a single operator to manipulate, and when the railway car is in motion, steel hatch covers may be very noisy due to 15 vibration transferred through the car.

An alternative to steel hatch covers is fibreglass.

While fibreglass is durable and is not subject to the same kind of failure due to fatigue as steel, fibreglass hatch covers may be relatively expensive to manufacture and cannot be manufactured in large numbers quickly except with very expensive equipment. Whilst fibreglass is significantly lighter than steel, it is still relatively rigid and may eventually fail due to fatigue caused by constant vibration caused by movement of the rail car along a railway track.

Accordingly, there is a need for a durable hatch cover made from a material other than steel or fibreglass which has a long serviceable lifespan, can be manufactured in large quantities at a reasonable cost, is resistant to stress caused by vibration transferred through a rail car, JL 0477i -I I I

I~

4 and provides a safe surface which can be walked on by an operator during filling operations. Although thermoformable polymeric materials may have been considered for use in such applications, hitherto no suitable structure has been devised which can provide the necessary strength yet being light enough for a lone operator to manipulate.

According to the present invention there is provided a thermoformable polymeric hatch cover having an upper deck, a lower base panel supporting said upper deck and a void therebetween, said upper deck comprising a plrality of transverse upper panels and lower panels, adjacent edges of each upper and lower panel joined by a side wall so as to form a corrugated surface and where each upper 15 panel is arched longitudinally across the width of said upper deck.

Preferably the upper deck and base panel are formed integrally and are joined to each other around their perimeters by a connecting web.

The void between the upper deck and base panel may be an air-space formed during manufacture of the hatch cover. When the void is an air-space the weirht of the hatch cover is significantly reduced compared to a hatch cover with no such void.

The upper deck comprises a plurality of transverse upper panels and lower panels. Adjacent upper and lower panels are joined along their adjacent edges by a side wall. Preferably there is an alternation of upper and lower panels along the majority of the lengt:h of the upper deck such that the majority of the upper deck is in the JL 0477i L 5 form of a corrugated surface consisting of arched transverse bridges with channels therebetween running across the width of the hatch cover.

Each upper panel is arched longitudinally across the width of said upper deck. In a preferred embodiment the ratio of the radius of curvature of each upper panel to the width of said upper deck is between 1.00 to 2.00, more preferably between 1.10 to 1.60. Most preferably the ratio is about 1.30. In a preferred embodiment each lower panel is substantially flat across the width of the upper deck. In this embodiment the side walls are arcuate, each side wall having a linear edge joined to a lower pariel and a curved edge joined to the adjacent upper paliel edge. In one embodiment, the linear edges and the curved edges of 15 each individual side wall meet at the sides of the upper deck. The planes of the side walls joined to a singlF lower panel may be parallel, such that a channel running between adjacent upper panels is substantially rectangular in transverse section with the depth of the channel reducing towards the sides of the upper deck. In another embodiment the planes of the side walls joined to a single lower panel converge in the direction of the base panel such that each channel is trapezoid in transverse cross-section.

The upper deck provides a walkway surface upon which an operator may walk during filling operations. Each upper panel must be arched longitudinally across the width of the upper deck. The curvature of each upper panel is preferably such that an operator can walk along the upper deck safely the upper panels not being so curved as to JL 0477i

I

6 present a steep surface which may be hazardous to the operator.

In a preferred embodiment the transverse upper panels are provided with grip means to prevent persons from slipping when walking along said cover. The grip means may be a plurality of raised lugs. The grip means may be a rough-textured surface on the transverse upper parels. The grip means is preferably capable of providing a non-slip walking surface even when wet. Additionally, the channels formed by adjacent upper and lower panels may assist in draining the upper deck of water after rain.

The base panel may be provided with reinfcrcin means to prevent deflection of the hatch cover when being walked upon by an operator. Preferably the reinforcing oo 15 means is a plurality of hollow ribs. The hollow ribs preferably extend substantially along the length of the base panel perpendicular to the direction of the upper panels. Preferably the ribs in transverse section are trapezoid.

The hatch cover is manufactured from a thermoformable polymeric material. Preferably the hatch cover is mide from a linear low density polyethylene although other suitable thermoplastic polymers known in the art may also be utilized, The preferred method of manufacture of the hatch cover is by way of a rotational moulding process. In this process a measured quantity of polymer is placed in a closed hollow mould. The mould is then rotated about 2 axes which are perpendicular to each other. The rotation distributes the polymer on the inner walls of the mould where heat from an outside source JL 0477i I_ 7 converts it to a liquid phase. By cooling the mould the hollow hatch cover is solidified whereupon it can be removed from the mould.

It will now be convenient to describe the invention with reference to a preferred embodiment illustrated in the drawings.

Figure 1 is a plan view of a hatch cover made in acc, nce with the present invention shown from beneath the cover.

Figure 2 is a plan view of a hatch cover made in accordance with the present invention shown from above.

Figure 3 is a longitudinal section along the line A :Figure 4 is a transverse section along the line BB'.

Figure 5 is an enlarged detail of co-operating interlocking portions on adjacent hatch covers.

Hatch cover 1 is generally elongate and is of a suitable size to cover the width of a rail car hatch. A series of co-operating hatch covers may be provided to cover the length of the hatch, each hatch cover closing a portion of the hatch thus allowing an operator to open all or only part of the hatch as desired. Furthermore, when a series of hatch covers are provided to cover a single ooooo hatch the resultant reduction in size of each hatch cover accordingly reduces the weight of each hatch cover and thus makes handling easier for th3 operator.

The hatch cover 1 comprises an upper deck 2 and a base panel 3 and a void 4 therebetween. The upper deck 2 and base panel 3 may be joined about their perimeters by a connecting web 3a which may be formed integrally with the JL 0477i 8 upper deck 2 and the base panel 3. The base panel 3 consists of a plurality of ribs 5 which run longitudinally along the length of the hatch cover. Preferably e ribs are trapezoid in cross-section to achieve optimum strength. These ribs 5 act to stabilize the natch cover along its length. Particularly when a person is standing in the middle of the hatch cover, the ribs 5 pievent or minimize the deflection of the hatch cover along its length.

The hatch cover 1 may further be provided with longitudinal recesses 6 on either or both sides of the cover which overlie corresponding raised portions about Sthe opening of the rail car. The recesses 6 and raised portions co-operate to seal the hopper of the rail car S 15 from rain, dust etc.

The hatch cover 1 has an upper deck 2 which comprises a plurality of transverse upper panels 7 and lower panels 8. Adjacent edges 9 and 10 of transverse e o eo2. upper panels 7 and lower panels 8 respectively are joined by a side wall 11 so as to form a corrugated surface as shown in Figure 4 Each upper panel is arched longitudinally across the width of the upper deck as shown in Figure 3. The ratio of the radius of curvature R of ooote2 S•each upper panel to the wdith W of the upper deck is most preferably about 1.30. In a standard rail car with a hatch opening of about 800 mm, the preferred radius of curvature R is between 800 mm and 1600 mm.

Preferably the channel 12 formed by two adjacent side walls 13 and 14 and a lower panel 15 is trapezoid in transverse cross-section. Each rib 6 in axial section has JL 0477i 9 a convex roof. In transverse section the ribs may be trapezoid. In another embodiment, the channels 12 may be rectangular in cross-section where the side walls are both vertical.

The plurality of upper panels 7 form a walkway surface upon which workers may walk during filling operations. The upper panels include a non-slip surface comprising a plurality of raised elements 16.

Each hatch cover may be attached to the rail car by a hinge 17. Preferably, each hatch cover 1 is attached to the rail car by two-way hinges which allow the hatch cover 1 to be opened either to the right or the left of the rail car as desired. Each hatch cover 1 may be provided with a handle 18 to facilitate opening and closing, and a locking 15 mechanism as is known in the art to secure the hatch cover in a closed position when in transit.

Adjacent hatch covers 19 and 20 may incorporate co-operating interlocking portions which form a o e weatherproof seal. Co-operating interlocking portions may consist of an overhanging lip 21 on the end of one hatch *cover which engages in a recess 22 in the end of the adjacent hatch cover. Th3 co-operating interlocking portions are preferably formed integrally with part of the coo e S• connecting web 3a at the ends of each hatch cover i.

It will be apparent that various modifications and/or additions may be :ade to the above described embodiment without departing from the spirit of the invention.

JL 0477i

Claims (9)

1. A thermoformable polymeric hatch cover having an upper deck, a lower base panel supporting said upper deck and a void therebetween, said upper deck comprising a plurality of transverse upper panels and lower panels, adjacent edges of each upper and lower panel joined by a side wall so as to form a corrugated surface and where each upper panel is arched longitudinally across the width of said upper deck.

2. A thermoformable polymeric hatch cover according to claim 1 wherein the ratio of the radius of curvature of each upper panel to the width of said upper deck is between 1.0 and

3. A thermoformable polymeric hatch cover according to S 15 claim 2 wherein said ratio is between 1.1 and 1.6. S.

4. A thermoformable polymeric hatch cover according to any one of claims 1 to 3 wherein said upper deck and basepine are formed integrally and are joined to each other around their perimeters by a connecting web.

5. A thermoformable polymeric natch cover according to any one of claims 1 to 4 wherein said lower panels are substantially flat across the width of the upper deck.

6. A thermoformable polymeric hatch cover according to any one of "laims 1 to 5 wherein said transverse upper panels include grip means thereon.

7. A thermoformable polymeric hatch cover according to any one of claims 1 to 6 wherein said base panel includes a plurality of hollow reinforcing ribs, extending Ssubstantially along the length of said base panel. T O 30

8. A thermoformable polymeric hatch cover according to JL 0477i 11 claim 7 wherein said ribs are trapezoid in transverse cross-section.

9. A thermoformable polymeric hatch cover substantially as hereinbefore described with reference to any one of the drawings. DATED: 17 MAY, 1994. PHILLIPS ORMONDE FITZPATRICK ATTORNEYS FOR:- NYLEX ROTOMOULD PTY. LTD. 0477i 0 c JL 0477i ABSTRACT A thermoformable polymeric hatch cover having an upper deck, a lower base panel supporting said upper deck and a void therebetween, said upper deck comprising a plurality of transverse upper panels and lower panels, adjacent edges of each upper and lower panel joined by a side wall so as to form a corrugated surface and where each upper panel is arched longitudinally across the width of said upper deck. 6* 2 2 o