Some options for the 2T base

This basic prototype at Cambridge shows the carcass/shell mounted on the base with a tilt hinge at the level of the fulcrum.   The base is a standard 5 star.   Greater stability when reclined would be improved if the back 2 legs were extended.   This suggests that the rotation of 360° would need to be reduced to about 60° in the anterior direction.

The post Hospital beds shows a number of beds each with a base of great complexity.

    Ankit

The Ankit model has a simpler base.  It is possible to incorporate a hinge mechanism onto this sort of 4 wheel base to support the functional carcass.    

• For this
• The hinge would be at the apex of the base.
• The hinge could be mounted at the fulcrum
• or at the front edge of the seat-pan.
• Damping is required to avoid a jolt at the end of range.
• The base can be narrower or wider than the carcass.
• The latter is more stable.
• Consider :-
  • The mounting of the arm-rests, if any.
  • A shelf, shelves.
  • side restraints for a hospital bed.

• See Hospital-applications/→
• Hospital beds→

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To design a hospital bed to a new concept a knowledge of existing thinking is helpful, with a quick Google search.

• A 2T version would be a major advance on most of them in cost, versatility and comfort.
• Simple and inexpensive
• Allows user movement
• Incorporates the emergency Trendelenberg position.
• Allows a more user friendly position for cervical traction.
• Allows the patient to lie fully flat horizontal.
• Lying on side, prone or in the recovery position is possible.  The slight ‘iliac’ support would be lying above the pelvic brim and limit slippage if the head end is lowered.  The slightly elevated legs aids venous return.    It can be addressed by increasing the seat/back-rest angle or having these components hinged (an added expense).

Return to ← Hospital Applications

A simple hospital bed.   

Retails at £340.

• A home bed with a backrest and some contouring.
  

• ‘Xb Hospital Bed Profiling Nursing Bed Patient Bed Care Bed Multi Function Electric Smart Home Care Bed Manual Adjustable ‘    from £2,616.97.    The hype states :-
• Backrest and Leg Lifting: Adjust bed to a comfortable position to meet amusement, dining, reading and cleaning.
• Leg up & Leg Down: Relax patients legs, promote legs blood circulation, preventing varicose veins and easily for legs’ daily care.
• Backrest Lifting: Patients can sit up and do some daily life activities easily, lessening nursing burden for both patients and nurses.
• Easy full body lift for nursing and working.

• Looking at these beds, a few ideas emerge to comply with a 2T version.
• The bed-end would become a variable foot-rest enabling exercise of the calf,
• The side restraints could be added at will.
• The short base wheels would be back at the level of the end of the seat-pan.  (Tipping might occur if someone should sit distal to this point).
• This allows the bed to be transformed into a wheel-chair.

• Adjustable head-rest, foot-rest and leg-raise would be integral.
• The Trendelenberg position available for emergency use.

At Last!   A brave effort going some way towards the 2T concept.  It looks awkward, over-engineered  and is anything but simple.

Ankit

Ankit Polyweave Industry provide vast range of best quality hospital bed and other hospital equipment in India.

Expensive, complicated compared to a 2T model.

Another example.   The ICU Electric economy model GM7002.   Instead of a simple 2T tilt the carcass is moved forward to achieve a wheelchair mode.

HILL-ROM TotalCare Sport 2 P1900M

Electric Hospital bed.  Asking Price :$5,995.00 USD.   At least it has an upright mode.

The carcass/shell of this model is near correct, except for poor contouring.   A 2T version would be simpler.   Note that the front wheels of the support are below the front edge of the seat-pan which allows a wheel-chair mode.  This has been made awkward by the undue depth of the seat.   Check with the advised dimensions of the 2T version to see how this could be improved.  Could a visitor sitting on the leg-rest tip the whole bed?   Unlikely, I think.

It can be seen that a 2T version has the potential to be a major advance on most of these in cost, versatility and comfort. 

• Return to ← Hospital Applications
  
• Or the-2t-base

For HOME & CLUBS

Hitherto  the concern of this work has been only for ‘ergonomic’ work-chairs.   Chairs for the home have been rather ignored as their ergonomics are unimportant compared to chairs required for prolonged work.    Since looking at chairs from a  bio-mechanics viewpoint,  almost all show a total disregard, or oblivion, to even basic concerns for spinal well being.   Designers are obviously ignorant of these factors although comfort also depends on them.   However there should be no excuse for designing a chair that is liable to give spinal dysfunction, or can be categorised as ‘A machine for making Backache’.    The boundaries between contract and home furniture  are decreasing and the division may be disappearing entirely. 

Christopher Bellew wrote in his daily blog “I was a guest at luncheon in a London club and fell into conversation with an affable member in the bar after lunch. His name is Dr Henry Sanford.   After some general chit-chat we digressed to his working life.   After a life time in Orthopaedics, he told me that his patients with backache would ask him to recommend a chair that would not make their problem worse.   I have a suspicion that his invention owes much to his observation of recumbent members of his club after lunch. The Savile would be an admirable name for a chair …”

 It can be seen that the typical club chair makes no pretension to ergonomic concerns.   They are irrelevant as the chairs are not intended for prolonged use and only have  to look comfortable.

The aged Intervertebral Disc. (IVD→)  and the lengthened seat-pan allows a slouched posture which is not seriously adverse.

Easy chairs in the home

Much the same applies to chairs in the home which are not intended to be work-chairs.   Recliners are for home use and probably used by those who sit, or even sleep, for long periods.  As they have features similar to the 2T (3M) concept they have been considered separately.   Will people buy recliners when a cheaper and better designed dual purpose chair comes on the market?  This may also be particularly relevant to the growing ‘gamer’ market. (Recliners→).

The ‘Saddle Chair’ by Timothy  Oulton, at his fantastic new premises in the old Bluebird workshop in the Kings Road, caught my eye.   It is almost reclined with no other concern for ergonomics.  Still on an equestrian theme, Mandal advocated a Forward Tilted Seat.   With a FTS and the back rest with pelvic support this would become an interesting ergonomic chair and the improved ergonomics would also add to the comfort.   The other chairs on show look comfortable and are mostly heavily upholstered.   I am told that this is a good selling point – “After all, they can always use a strategically placed cushion” but would probably be avoided by anyone liable to backache, who would know better.   If the upholstery was of denser foam at the level of the iliac (Pelvic) crest the appearance would be the same but pelvic support would result. ( BACKRESTS. Pelvic support v. Lumbar.→).

The Eames Chair.   Yes.  This seems to be the best easy home chair.   I have ignored it, not being a work-chair, but it does have some 2T features, a reclined mode and leg support, which accounts for it’s comfort.   For me, It is not an ‘Object of Desire‘.   I do not like it being in two bits when there is a one- piece solution which could be more elegant, simpler and to the contemporary taste using the 2T (3M) concept.   Being more ergonomically compliant it would also be even more comfortable.

Roorkee chairs

For the ‘cool’ uncluttered look a simpler chair is possible.   The old Roorkhee campaign chair which had some ergonomic advantages has many modern derivatives. Some of these advantages having been lost in translation.   It is chairs of this sort that are popular with Interior designers although the ergonomic advantages vary. Roorkee chairs have spawned a number of modern designs including Klint’s Safari Chair and also by Marcel Breuer (the Wassily chair), Le Corbusier (the Basculant Chair), Wilhelm Bofinger (the Farmer’s Chair) and Vico Magistretti (the Armchair 905).

Roorkee chairs are campaign chairs with marvelous design  used in the Army from 1898 to WW2, ‘officers , for the use of’.     The pair from my Uncle Jack (Berrington) during the South African Boer War (c. 1902) was lost in transit so he indented for two more.  The original pair reappeared and now I have all four.  Here is his Brother in Law, my Uncle Gilbert and his sister (Aunt Alice Berrington) sitting in Roorkee chairs in about 1950.   He is in a reclined position and the bottom edge of the tilted back rest gives some pelvic support, and this unexpected ergonomic efficiency is why officers may have found it so comfortable.   Hers has an additional headrest which would allow a sleep mode.
Developed by the Indian Army Corps of Engineers in Roorkee, India, the Roorkee chair is lightweight at about 10 lbs., and breaks down quickly to be stored in a 9″ x 36″ canvas bag.   The ingenuity of the design lies not only in its ease-of-assembly and dis-assembly, but the very act of sitting in the chair reinforces its structure.  The seat canvas is slung between front and rear crossbars and pulls them towards each other, tightening the side rails in their mortises with the legs.

My Roorkee chair, disassembled.  Shows the backrest.  The original canvas was lighter in colour, replaced here with army tent canvas.   The front strap may have been added later, and broke when being assembled today (17/Nov/2018, not bad after over 100 years).    Assembling needs some expertise which batmen (soldier servants) must have learned quickly.  How it can be done is shown, using a modern version at https://www.youtube.com/watch?v=nwPqQSYUCvM .   Also it requires expertise to get the parts into such a small canvas bag.  The original bag 90 x 23 cm.

The ergonomics, I discovered, are good.   Leaning backward results in rotation of the backrest with a slight extension force on the thoracic spine and  extension of the lumbar spine.   This comes close to the 2T CONCEPT  and accounts for it’s recognised comfort.

Compare the position of the user when sitting in a 2T prototype showing an optimal work position.

Core 77 has an account and show a number of archive photographs of the chair being used including one  of Gen. Earl Alexander, sitting in a Roorkee chair beside Churchill,  in a less comfortable upholstered (no correct back support) arm chair, who would have known Roorkee chairs well from his time serving in the 4th Hussars.   

(See https://www.core77.com/posts/65226/MCM-Furniture-Design-History-The-Safari-Chairs-Military-Roots).

From a wierd concept in 1998 to become disruptive in 2017?

The ‘Deskless Chair’ derived from the ergonomic importance of a reclined work position, is morphing into the ‘Workstation’. This should reduce the incidence of LBP and other health issues.

In 1903 Ford’s ‘Horseless Carriage’ had morphed into the Model T, capable of 20 horsepower In 1908.  This, at least, solved the “great horse manure crisis of 1894” when it was suggested that London’s streets would be clogged in 9 feet of horse manure in 50 years. It’s descendants are, in turn, being disrupted by ‘the driverless car’.

Disruptive technologies have to prove themselves first. They do so by working on the same infrastructure as the incumbent leaders. Cars had to run on the same streets as horses. Dial-up internet connections in the late 1990s used the copper in the phone networks.  (Dan Denning Publisher, Southbank Investment Research ).   So, work-stations have to use existing office spaces before becoming universal.

We are seeing a number of ‘OFFICE WORK-STATIONS→’ type models which include a reclined work mode and so are superior to the present (2016) upright conventional  models.  The models shown here are a step in the right direction but are not 2T compliant and appear to ignore the science and are based on engineering.    They do not invite a great uptake, in spite of extensive PR.  WORK-CHAIRS, a new breed with a reclined mode →

The simple upright office chair

This has improved.    Although not 2T sophisticated the designers of the following may have seen my posts.  This advert arrived in my post today (27/11/2019).

At least there is an apology for pelvic support and a headrest.

For further reading, see ☛

• An account by Dutch futurologists → The end of sitting?
• How major factors will impact on sitting → The global future?
• The 4M concept and OFFICE WORK-STATIONS→
• A way that tech.is going → VR and sitting
• A treacherous guide → COMFORT
• Designers beware → Familiarity bias

←Return to  ☛ 2T CONCEPT a full solution

This highly innovative chair was introduced to me by it’s designer,Thomas Stroman, the Founder of Stroman Design.   He wrote to me “I am an architect by training, but having experienced back surgery, my focus has been on ergonomic seating design for human-computer interaction.  Over the past three years I have designed, prototyped and patented the Chotto® ( chair + ottoman ) .  It is a uniquely human-centric and recumbent seating / task-seating / standup desk that positions the body
into close proximity to the neutral body posture that is produced in microgravity.”  “I believe  this field of study is increasingly important and needs to be pursued given the scope of benefits it can provide those who must sit by choice or physical condition. I would also like extend an open invitation to you to evaluate my prototypes if you are ever in NYC.    Regards,  “

An excellent objective and a very interesting product.  At first glance I might be excused for thinking that it looked as if it were self mobile with caterpillar tracks.  Perhaps an exciting concept for the future.    I wrote back (May 19, 2017)

Dear Tom    I have had another look at your web page  www.stromandesign.com​  At first sight, I admit, I thought the Chatto to be OTT.  But on second thoughts, some might find it attractive, including me, to charge around an open plan office floor in a mini-tank.  But I can see it excites ‘familiarity bias’.  I can see no reason why it cannot be modified to take advantage of the 2T ergonomic optimisation.   This would be a huge selling point.  Even the Chinese put ‘health’ as their top design requirement  Unlike our chair manufacturers who put ‘comfort’.  (See http://sittingsafely.com/comfort/ ).
In the early model, above, I was worried about the apparent calf compression that has the potential for DVT.  “An optional footrest elevates the legs and feet while an immediately mobile, nested and freely rotating task tray provides a universal surface for eating, reading, writing, or digital interaction. This same tray can be repositioned within the optional rear support brackets for use with the pivoting display interface / standup desk ( PDI ).  The PDI is based on design research that favors a human-centered interface that literally revolves around the seated, tension-free and fully supported user.  If paired with a laptop, the PDI can also be used as a dual-screen interface in both the seated or standing position.  With the PDI in the default standup desk position, the Chotto simultaneously accommodates both a standing and seated user – all within a small 15 s.f. footprint.”

Also the user is very happy but looks trapped.   How does she get out?   Leg support is unecessary as it is provided by the long bones of the leg but a foot rest is essential, padded support for the heels, for prolonged work but not for the upright mode.

Dear Tom.     Looking at your diagrams, I would make the following points from the bio-medical viewpoint :-

• You have a good reclined work position.  But the Chair /body shape interface requires  iliac support at 20 cms above the seat pan. This is important for spinal wellbeing.   (See http://sittingsafely.com/2t-reclined-mode/  bottom half).
• You have correctly spotted that good design encompasses most body shapes and sizes.  Adjustment is only needed at the extremities, neck and legs.   (See http://sittingsafely.com/adjustment/ ).
• I like the way your computer screen adjusts to whichever mode.
• For full 2T compliance I make a point for the intermediate ranges to be unstable for additional health benefits.  Of course, this is not basic (See http://sittingsafely.com/exercise/ & http://sittingsafely.com/the-unstable-intermediate-mode/ ).
• On further thought, I do not think that a lordotic concave support for the kyphotic/convex thoracic spine, as described in the 2T is strictly required.  The thoracic joints are stable being splinted by the ribs.  Only rotation movement occurs at this spinal level.
  Your configuration depends on the convex shape of the wheel circumference and this can support the fairly solid thorax, providing that it is accompanied by neck/head support in the reclined mode.  You will be glad to hear that I have tested this while having my bath.  In the UK we have prolonged baths and so can think great thoughts.  The iliac support, lower down at the lumbar-sacral junction is very important but can be effected by padding as you have suggested,
   
  Best
  Henry

Another architects chair

Architects have a tradition for designing good furniture. Aaron Chetwynd did this 2T sketch for me. It is deliberately ‘office chair’ looking to reduce ‘familiarity bias’.   It is not intended to be a work-station.

 Tom

The leg/foot-rest design is important and is wrong in the Aaron view above. There is no need for a leg rest as this is effected by the strong long bones of the leg (Lower end of the femur & lower leg tib/fib).  However this brings point pressure onto the heels which I found to be painful over time and needs to be well padded.  I think your design shows this except the pressure seems to be at the ankles.  This may need further consideration. Also it needs adjustment for leg length.  Pressure on the calf muscles should be avoided as it may limit venous return and cause Deep Vein Thrombosis.

New point

See http://sittingsafely.com/2t-3m-commercial-implications/

About the Chotto:

LBP. Cause (Aetiology).

The causes of LBP are multifactorial  and ill understood.    It is suggested (Adam et al.2002)  that  there is a need to integrate the evidence from genetics, biomechanics, biochemistry, cell biology and psychology to construct a comprehensive model.

Twin studies suggest that only 70% of the UK population is liable to LBP (Spector 1999). Other twin studies strongly emphasise the genetic factor in the aetiology of LBP  (Battie et al., 2002).   Genetics are not a cause of LBP but a risk factor acting through, possibly, spinal configuration or components of the disc composition.

Psycho-social factors, regarded as an important in the large increase in the last 20 years (Waddell 1996), is  more a response rather than a cause, resulting increases reporting.     Anecdotal evidence from patients with chronic LBP should not be ignored.  Although usually unaware of any causative incident, they are fully aware of what makes their symptoms better or worse.

The prevalence and incidence of LBP in populations that do not use Western style upright chairs but other ‘natural’ styles of sitting. which are culturally determined, is very low or nil, suggesting an adverse effect of the use of Western style upright chairs.    In Japan, this increases as elements of the population adopt Western chairs (Schlemper 1987).

Nutrition, environment and lifestyle may all play a part in the aetiology of LBP, but the only new factors that might account for the present epidemic is lack of exercise and a sedentary Western lifestyle.    Driving, office work, computers and TV,  the modern worker spends an increasing amount of time in a chair.

Epidemiological studies of  backache prevalence.

The literature on epidemiological evidence is extensive but, in relation to aetiology, confusing due to uncertainties and imprecision in describing reliably the condition that is under review.  Low back ‘trouble’ extends from LBP of psycho-genic origin to a midline IVD protrusion causing a corda equina syndrome, which is a surgical emergency.  Meta-analysis of systematic reviews, useful for evidence based therapeutics, have to be viewed with caution in extrapolating to clinical conditions. (Furfan et al 2001).  I have often seen wrong conclusions in my own field.

A study by the US Department of Health and Human Resources (NIOSH 1997) reviewed a number of factors and the general conclusions seem to suggest that the evidence was contradictory and confusing. There was an emphasis on non-physical psycho-social factors and heavy load handling.   Much of the research into the causation of spinal breakdown has concentrated on violent or inappropriate spinal usage afflicting manual workers today and hominins in prehistory (See Origins of lumbar vulnerability→).

In a Swedish review (Linton, van Tulder.2001) of controlled trials of preventive interventions for back pain problems only exercise gave evidence of relatively moderate significance perhaps suggesting that sitting has no influence on LBP.   The divergence of the  clinical and other evidence from that of some epidemiological studies suggests that the methodology of the latter should be reassessed rather than an immediate conclusion that seating plays no part in the symptomatology of LBP.

Invisibility is possibly due to  the universality of the upright sitting posture on chairs becoming  a part of the human condition in Western orientated populations, so that it fails to become apparent to recognition in systematic reviews.  This impacts on research, where musculo-skeletal funding is minuscule, in spite of the economic, which is about £13billion annually in the UK, and personal cost .