I’ve noticed that on hook and ladder rigs (I think that is what they are called, but don’t know why that is so, either - I see the ladder, but where is the hook and what would you need a hook for??) that on the hose nozzle there is an heavy s-shaped hose that the water passes through just before it leaves the nozzle. Must be some good reason or they wouldn’t put all that metal at the end of a long ladder. I’ve seen those long spike - shaped nozzles also, and I’m told they are used to poke through the roofs of houses to put out fires on the inside. That makes sense to me, but why the curvy thing?
Uh, that would be HOSE nossle, I mean nozzle.
I don’t have a link to a photo, but a shape as you describe is often used to incorporate the swivels that allow the nozzle to be aimed. There are two axies of movement, one horizontal and one vertical. In photos I’ve seen of fireboats they use a similar system that has two control wheels, one for each axis. Take a look at this photo www.nautilus.org:8080/gr/ peg-fireboat-2001-08-16.jpg
Well I copied the link from a Google search of fireboat, but now it doesn’t work. And I took out the space between “gr/peg_” too.
The “hook” of a hook and ladder rig refers to the hitch where the ladder trailer connects to the engine rig. Just as on a tractor/semi-trailer rig the hitch area is called a “fifth wheel”, on a fire department’s large ladder truck it’s called a hook. Same thing, different name.
As for the curved loop in the nozzle assembly, some of it allows for adjusting the aim, and some of its purpose is to direct the back-thrust of the water into the mounting brackets, rather than cause the nozzle to spin or whip around uncontrollably.
The picture mentioned above can be seen at:
YiBai is correct, plus, the bend in the pipe also saves the stress on the ladder and hydraulics by not causing a direct and immediate force backward against the ladder.
Fire Vehicle Nomenclature, for the record:
Engine: Normal Fire Engine
Truck: Ladder Truck, traditionally without a pump, more often now though, pumps are mandatory.
Squad: Dedicated rescue unit, traditionally without a pump, sometimes with one, it’s the ‘tool box’ of the fire service.
Snorkel: Truck with a bucket, but no ladders to climb, entry from the ground, controls in the bucket
Quint: Engine, with small attached ladder or bucket, and squad capabilities
Hook and Ladder and Tower Ladder are somewhat antiquated terms, but still in use none the less.
Hey, you guys are great.
It is hard for me to understand the physics of why having that s-bend in the pipe would cause a change in the direction and/or power of the force on the end of the ladder or mounting brackets, unless it slowed down the velocity or mass of the water leaving the pipe (which seems self-defeating). Now the mass of the thing might keep it from bouncing around so much.
Fishhead
Hey, you guys are great.
It is hard for me to understand the physics of why having that s-bend in the pipe would cause a change in the direction and/or power of the force on the end of the ladder or mounting brackets, unless it slowed down the velocity or mass of the water leaving the pipe (which seems self-defeating). Now the mass of the thing might keep it from bouncing around so much.
Fishhead
Hey, you guys are great.
It is hard for me to understand the physics of why having that s-bend in the pipe would cause a change in the direction and/or power of the force on the end of the ladder or mounting brackets, unless it slowed down the velocity or mass of the water leaving the pipe (which seems self-defeating). Now the mass of the thing might keep it from bouncing around so much.
Fishhead
Hey - did you get that? I said… (lord what a dummy I can be sometimes) :smack:
Almost, IIRC its more to do with more gradually making the bend to the nozzle so there is less stress and or turbulence in the line right at the nozzle.
Also there is still immense amounts of force being directed back at the ladder generally referred to as nozzle reaction. 100’ aerial ladders will flex back 5-8’ from this thrust generated by the nozzle
Puts water on fire
Truck technically refers to a piece of fire apparatus with over a certain amount of ground ladder capacity. Aerial devices are actually optional in that respect.
In big citys, trucks usually carry most of the heavy tools n stuff, depends on your jursidiction
Quad = triple combination(normal) engine = larger ground ladder complement or aerial device
quint = above with both truck grade ladder assortment and aerial device.
I was under the impression that the “hook” referred to pike poles, used for tearing open ceilings and suck.
Looking at the photo, I think the complex curve is necessary because a swivel joint has to be in-line with a straight tube. At such high pressures it’s difficult to make a simple bend with an adjustable bend angle. Instead you incorporate a swivel joint in the middle of a straight tube so the tube can “twist.” So for an up/down angle adjustment, one section of the tube must sideways (horizontal and perpendicular to the nozzle). You also need a vertical section for the sideways motion.
Another constraint is that the nozzle (the actual water jet) must be in-line with both swivel axes. Otherwise the force of the water jet will tend to twist the nozzle around. If you look at the photo linked above, there is one swivel mechanism in the vertical section before the first bend, and another swivel on the lower horizontal part. Then you need to bend the tube back to the middle so it’s in-line with the vertical axis swivel. The tube is then bent forward and up so it aligns with the horizontal axis swivel.
(I’m sorry if I mangled the terms for the various components, I’d appreciate corrections.)
Just wanted to clarify on why they are called Hook and Ladder companies
Ladder trucks are used for interior ventilation, roof work, and salvage
The ladders are used to gain access(of course) but items looking like large pike poles and shorter items that look like a shovel handle with a hook on the end( a closet hook) are used to rip open ceilings to look for fire extension and other hazards.
Modern Ladder trucks do lots more but way back in the day that was about all they did. They didnt do much interior fire fighting mostly surround and drown and using long poles to push in the building’s walls, to keep them from falling outwards, was a common tactic.
Most Volunteer Fire Companies were formed way back in the day and might have been incorporated with a name like “Straight Dope Volunteer Hook and Ladder Company”
The Fire Dept is steeped in tradition and probably wouldnt have changed the name.
As the others have said regarding the curve to a master stream appliance, it is to incorporate the swivels in the up/down and side-to-side axis. Depending on what manufacturer of aerial you have, the age of the truck, and whether or not it is a pre-piped waterway (a 3"-4" pipe bolted to the underside of the ladder), you may or may not have side-to-side abilities.
The old method of flowing water from an aerial is to run a hose up the ladder, and clamp the nozzle to the top rungs. Run a pair of ropes to the ground, and you have your aerial master stream. To move the stream of water from side to side, you move the ladder itself. The older ladders weren’t tolerant of torsional loads, so you can’t direct the stream more than 5 degrees off-center.
Newer ladders may have a prepiped waterway with a remote-controlled nozzle at the tip. Two or three switches at the turntable (and another set at the tip) move the nozzle to the desired direction and change the pattern from fog to straight stream. As far as I know, all of the manufacturers today allow ~180 degrees of motion (90 to each side) with prepiped waterways. Since you add in side-to-side motion, another swivel in the pipe is needed.
Regarding the “Hook,” the term itself comes from the olden days of firefighting. The hook was a tool used to pull down walls of buildings to stop the advance of a fire. Today we put water on a fire and knock it down. Once upon a time, the tactic was to pull down the buildings around the one on fire so the fire wouldn’t spread. The companies that did this were the folks that also brought the ladders to the scene, thus “hook and ladder companies.” Since firefighters are stubborn creatures of habit (sorry, “traditionalists”), we’ll still use the same term. Today, the “hook” is a pike pole, or a 6’ to 12’ long pole with a 4" hook at the top, used to poke through and pull down ceilings. We’ve got a shorter one (around 2’ long) called a closet hook, since you can get into a small space with it.