- If the upright ladder is not secured at the foot to prevent it slipping (which it isn't) then it could easily loose grip under the load, even in dry conditions.
- Even if the upright ladder was well bedded into the ground or tied so that the foot cannot slip the combined weight of two men plus ladder bearing down on it may well be close to the designed maximum for the ladder rungs to bear.
- If the upright ladder is at the optimum safe angle of 75 degrees it may not allow the man standing on it to exert enough upward thrust to support the man on the roof without propelling himself backwards (with or without the ladder he is stood on).
- If the man on the roof misses his footing (easy to do as the roof tiles prevent him getting more than just his toes on to the ladder rungs) the result will be like a 'domino derby'
Friday, 11 February 2011
Thursday, 10 February 2011
Tuesday, 21 December 2010
Asymmetric 'Support Pins' hook on to ladder stiles - fit is adjusted by slackening cotter pins(note missing yellow trim insert on rear support pin - see below)
- This is a great bit of kit for the professional ladder user - definitely the best ladder safety device I have tried to date - and I recommend them highly. But normal ladder safety considerations must still not be forgotten!!
- They would be a lot better if fitted with a quick release catch on the cotter pins to make it quicker and easier to swap between ladders. Some sort of built in carry-handle / loop would be helpful too. Because of this I only use my Ladda Limpets when I feel I really need to instead of every time I climb.
- Ladda Limpets work on any hard surface even if it is wet, slippery or loose like gravel. Indoors they won't damage floor coverings.
- They won't work where the surrounding surfaces are soft (like a small fish pond cleverly situated close to one of my customer's houses!) or where space around the base of the ladder is too restricted, perhaps by shrubs or other objects close to the foot of the ladder, which prevent the legs being fitted.
- If space around the ladder is limited fitting just one Ladda Limpet still offers better climbing safety than none.
- The splay of the Ladda Limpet legs considerably helps improve sideways stability too - very important if the top of the ladder is resting against a slippery surface like UPVC fascias or in windy conditions.
- The yellow plastic trims are a total waste and not worth bothering with - discard them.
here is a link to a Youtube video about the Ladda Limpets which shows how they work in more detail.
Additional information from the manufacturers website http://www.laddatec.com/
Sunday, 19 December 2010
Some friends of mine in the USA put this manikin up outside their house for a bit of a joke last Christmas but the joke backfired a bit when several passers by thought it was for real.
Tuesday, 30 November 2010
A number of manufacturers offer rubber protectors for the top of ladders to prevent damage to window sills and reduce the risk of the ladder slipping sideways. But just how good are these so called, 'Ladder Mitts'?
I have actually used a pair of these things myself for several years and always thought they were pretty good, now I know the facts I wouldn't lean a ladder against a sill or UPVC cladding without them. They definitely do prevent damage and increase safety. A number of my customers, who have previously had their window sills and frames damaged by other window cleaners that don't use Mitts, have been pleased to see the extra care I take with their property and commented accordingly.
Monday, 29 November 2010
- The top of the ladder was exerting a pressure of 15kg against the wall.
- Force acting vertically downwards on ladder feet. When I tried to measure this,, using another set of pulley blocks to hoist the bottom rung of the ladder vertically, the spring balance went off the end of the scale at 100kg without the ladder lifting at all. Maybe this was due to either: (a) friction between the top of the ladder and the brick wall -15kg of leaning force multiplied by friction co-efficient of rubber on brick- or perhaps (b) torque- the ladder is actually pivoting about the point of contact with the wall and therefore the weight is multiplied by the leverage created by the horizontal distance between where the weight is hung and the foot of the ladder (75cm) or (c) a combination of both.
- Although I didn't understand all the physics, one website I looked at seemed to suggest that the horizontal friction force preventing the ladder slipping was the same as the force pressing the top of the ladder against the wall = 15kg. But I doubt this as I could not move the foot of the ladder inwards at all. However without putting wheels on the bottom of my ladder I couldn't find a way to measure it.
- Additional force needed to cause horizontal displacement. On my driveway, rough concrete, I tried to pull the foot of the ladder away from the wall horizontally to test the amount of friction between ladder and ground. This actually proved to be very difficult to measure accurately as it was almost impossible to get both stiles to slip simultaneously but slippage generally seemed to occur at about 90-92kg = roughly the same figure as the combined weight of ladder plus load. This would seem to suggest that a 26 stone man (without any additional weight of tools etcetera) could climb the ladder to the same height without it slipping (but see 5 below) so at just under 11 stone I should be quiet safe on wet, but rough, concrete (warning note - the safe maximum working load for most portable aluminium ladders quoted by manufacturers is 150kg = 23 stone). HOWEVER, in my tests most often one foot of the ladder slipped before the other - sometimes at loads as low as 80kg - so it is absolutely imperative to make sure the ladder is placed with the load evenly spread between both feet and also not to push your luck.
- In reference to point 4 above - if you double the height of the ladder to 8 metres and distance from the wall to 2 metres the ladder will not allow 23 stone on the 4th rung from the top due to (a) The distance of the ladder feet from the wall has increased but the distance of the load from the wall is the same - therefore the load exerts more leverage (b) the size of the ladder feet is unchanged so the friction does not increase either.
- I also tried varying the angle of the ladder against the wall. At an angle of 68 degrees (foot 1.5metres from wall) the ladder only required a horizontal load of 74 kg before it slipped. Clearly not so secure but should be okay for a climber of up to about 24 stone. My driveway wasn't wide enough to try shallower angles but I know, from other stuff I've read, that below 60 degrees the grip of a ladder on the ground falls off dramatically. The condition of the ladder feet is also critical to how well it will grip.
Tuesday, 16 November 2010
The vast majority of ladder accidents occur because the foot of the ladder slides away from the wall that it is leant against, usually due to a lack of grip. Worn ladder feet or damp and frosty conditions make the situation much more dangerous.
If in doubt try 'The Boot Test'
Quite simply scuff the sole of your boot on the ground in the exact spot you intend to place your ladder and see how well it grips or if it slips. The sole of my boot (size 8) is about 20 square inches (125 square cm) of rubber. If that won't grip firmly on the surface you can be absolutely certain the mere couple of square inches of a pair of ladder feet won't either, especially at an angle with my weight at the top of it.
The solution is simple - secure the ladder to an immovable object or use an anti-slip device.
So don't take risks with ladder safety - put the boot in!