Support for a seat

A shock absorbing assembly for coupling to a pedestal for mounting a seat of a boat, the shock absorbing assembly including a shock absorber mounted in a housing, a pair of guide shafts being provided and being slidably mounted through the housing.

BACKGROUND OF THE INVENTION 
This invention relates to a support for a seat. 
More particularly, the invention relates to a support for a seat for use in 
a boat where occupants are subjected to buffeting when in rough water. It 
is to be understood, however, that the principles of the invention can be 
applied to other seats which require shock absorption. 
According to the present invention there is provided a shock absorbing 
assembly for a seat comprising at least one shock absorber coupled between 
the assembly and a support member for the seat. 
The support member for the seat may comprise a pedestal or the like. 
Preferably, the support includes at least one guide assembly comprising a 
guide tube and a guide shaft mounted for sliding movement in the guide 
tube, the assembly being coupled to the support member and the shock 
absorber to provide lateral support for the shock absorber. 
Preferably further, there are two of said guide assemblies. 
Preferably further, the support member includes a housing in which the 
shock absorber is mounted and the two guide assemblies are coupled to the 
housing. 
Preferably further, a compression spring extends between the support member 
and the housing. 
The invention also provides a shock absorbing assembly for coupling between 
a seat and a support structure for the seat, said mounting assembly 
comprising: 
first mounting means for connecting the shock absorbing assembly to the 
support structure; 
second mounting means for connecting the shock absorbing assembly to the 
seat; and 
shock absorbing means coupled between the first and second mounting means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates a boat seat assembly 2 constructed in accordance with 
the invention. The assembly includes a seat 4 and a base 6, the seat being 
connected to the base by means of a mounting assembly 10 of the invention. 
The base 6 includes a pedestal 7 with a mounting plate 9 connected to its 
lower end for fixing to the floor or deck of a boat. 
The seat 4 comprises a seat portion 12 and a back rest portion 14, the seat 
portion being connected to a seat support base 16 which forms part of the 
mounting assembly 10. The mounting assembly 10 includes a central housing 
18, the lower end of which is connected to the top of the pedestal 7 by 
means of a screw clamp 19. A skirt 21 projects downwardly from the support 
base 16 so as to cover the upper part of the housing 18. The seat 4, base 
16 and skirt 21 are all movable vertically relative to the central housing 
18 and pedestal 7. 
FIG. 3 shows in more detail the clamp 19. It includes a threaded shaft 100 
which is threadably mounted in a boss 102 which is formed integrally with 
the housing 18. A clamping block 104 is mounted for rotation on the inner 
end of the shaft 100. The block 104 is itself mounted for sliding movement 
in a recess 106 in the boss 102. An actuating knob 108 is provided on the 
free end of the shaft 100. The arrangement is such that the user can 
rotate the knob 108 in order to cause the clamping block to be moved 
inwardly and outwardly to thereby engage and disengage the outer surface 
of the pedestal 7. 
The mounting assembly 10 shown in FIGS. 2, 3 and 4 includes two hollow 
guide shafts 22 and 24 which are preferably formed from stainless steel. 
The upper ends of the guide shafts 22 and 24 are press fit into sockets 15 
formed in the underside surface 17 of the support base 16. The guide 
shafts 22 and 24 pass through aligned openings in the central housing 18 
so that the seat base 16 and guide shafts 22 and 24 are slidable 
downwardly relative to the central housing 18. The housing 18 is provided 
with upper nylon bushes 26 and 28 and lower nylon bushes 30 and 32 to 
provide relatively friction free sliding movement of the shafts 22 and 24 
relative to the central housing 18. 
The mounting assembly 10 includes a shock absorber 33 having a body portion 
34 and a projecting shaft 36. The shaft 36 passes through an opening in 
the centre of the support base 16 and is connected thereto by means of a 
nut 38, a washer 40 being interposed between the nut and the base 16. The 
shock absorber body 34 is mounted within a tubular support body 42 having 
a closed end 44. A lower fixing shaft 45 of the shock absorber passes 
through the closed end 44 and is connected thereto by means of a nut and 
washer 46 and 48, a resilient washer 50 being interposed between the 
washer 48 and the end 44. A wider diameter portion 52 of the support body 
is connected to the lower part by means of a shoulder 56. The upper edge 
of the wider diameter portion 52 is provided with a flange 58. The flange 
58 engages a shoulder 60 formed in a bore 62 which passes through the 
upper part of the central housing 18 to its upper surface 23. 
In the illustrated arrangement, the pedestal 7 is tubular and the top edge 
59 of the pedestal is received within the bore 62 and engages the 
underside of the flange 58. Typically the diameter of the pedestal 7 is 80 
mm and the diameter of the bore 62 and the portion 52 are chosen so as to 
have a relatively snug fit with the upper part of the pedestal 7. The 
lower part of the housing 18 includes an access opening 61 to permit the 
pedestal to enter the bore 62 as described above. It will be further noted 
that the body 42 and portion 52 as well as the shock absorber body 34 are 
located within the upper end of the pedestal 7. This makes the arrangement 
compact and robust. 
A compression spring 64 acts between the seat support base 16 and the 
shoulder 56 of the support body. The spring 64 surrounds the shaft 36 and 
part of the body 34 of the shock absorber. Washers 66 and 68 are provided 
adjacent to the underside surface 17 of the base 16 and the shoulder 56 to 
prevent these parts from being unduly worn by the spring 64. A relatively 
thick nylon washer 70 is mounted in the upper end of the spring 64 so as 
to keep the spring centred on the axis of the shaft 36. 
When a downward compressive force is applied through the seat portion 12 
the support base 16 will be moved downwardly against the resilient force 
of the spring 64 and the shock absorbing action of the shock absorber 34. 
This downward movement is guided by means of the guide tubes 24 and 26 
passing through the openings in the central housing 18. This provides a 
comfortable suspended seat for a boat which is travelling in rough or 
choppy water. 
In the preferred embodiment of the invention, the upward excursion of the 
seat base 16 is limited to a selectable amount whereby a preselected 
precompression of the spring 64 can be made. In the illustrated 
embodiment, this is achieved by providing limit washers 72 and 74 which 
surround the guide tubes 22 and 24. Movement of the washers 72 and 74 
(downwards relative to the shafts 22 and 24) is limited by means of 
retaining clips 76 and 78. The clips 76 and 78 are generally U-shaped but 
have laterally projecting legs 80 which pass through aligned holes 82, 84 
and 86 provided in the shafts 22 and 24. The holes 82, 84 and 86 are 
axially spaced along the shafts 22 and 24 and effectively limit the upward 
excursion of the shafts 22 and 24 depending upon which of the holes the 
legs 80 pass through. It is preferred that the preloading on the spring 64 
is in the range 30 kg to 60 kg and preferably 40 kg. The selected 
preloading is a desirable feature because it substantially eliminates 
movement of the suspension caused by relatively small movements of the 
boat. 
In the illustrated embodiment, secondary springs 90 and 92 are provided to 
provide additional resilience in the event of relatively large excursions 
of the seat 16 which for instance might be caused by the boat travelling 
in very rough water. The secondary springs 90 and 92 encircle the shafts 
20 and 24 but are significantly shorter than the distance between the 
underside 17 of the base 16 and the upper surface 23 of the central 
housing 18. In this way the secondary springs 90 and 92 will not be 
compressed until there has been about 40% to 70% and preferably 50% of the 
normal excursion of the suspension. It is preferred that upper and lower 
washers 94 and 96 be provided above and below the respective ends of the 
springs 90 and 92 so as to protect the surfaces 17 and 23 from wear. The 
secondary springs 90 and 92 have an uncompressed length of about 60 mm and 
a diameter of about 35 mm. 
It is preferred that the mounting assembly 10 is adjustable so that the 
excursion is in the range 50 mm to 70 mm and preferably 75 mm. 
In the illustrated embodiment, the base 16, housing 18 and shock absorber 
support body 42 are made from die east aluminium. It is quite possible 
that these components could be moulded from suitable plastics material 
such as ABS or the like. 
The shock absorber 34 can be of the type used in automotive or motorcycle 
applications. It may have an extended length of 294 mm and a compressed 
length of 187 mm, the body being about 34 mm wide. An Armstrong serial No. 
610400 is a suitable example. 
The compression spring 64 has a length of about 240 mm and a length of 125 
mm when fully compressed. The outer diameter is preferably about 60 mm, 
the wire diameter being about 6.3 mm. One suitable spring has been tested 
with a 50 kg weight and its length reduced from 240 mm to 196 mm. The 
characteristics of the springs 90 and 92 are such that 15 kg will produce 
about 20 mm compression for each spring. 
When the seat assembly 2 is mounted in a boat and the boat is buffeted by 
waves, the mounting assembly 10 acts as a suspension including shock 
absorption for the seat 4. More particularly, when the waves cause the 
boat's deck to rise, the pedestal 7 will rise but the full effect of this 
will not be transferred to the seat 4 and a passenger sitting on the seat. 
The inertia of the passenger and seat assembly will cause the shafts 30 
and 32 to slide downwardly (relative to the tubes 26 and 28) together with 
compression of the spring 24 and of the shock absorber 20. This 
substantially reduces the amount of movement of the seat 4 making the ride 
much more comfortable and safer for the passenger. 
It will be appreciated that the mounting assembly 10 can be used for 
supporting seats in other situations such as various forms of land 
vehicles and agricultural equipment and the like. 
Many modifications will be apparent to those skilled in the art without 
departing from the spirit and scope of the invention.