Trippers Et. Al.
Originally Posted by blakeyg
What are you all seeing as far as the current design trends for high capacity trippers or shuttling heads?
What I have seen lately are stiff tracks/support frames with stiff trippers/shuttles with large flanged rail wheels either side of moving car.
What happened to the flexible designs of the past that allowed for some misalignments?
What happened to only constraining 1 wheel and allowing the other to float?
I am looking at a lot of breaking wheels and structural failures on the new designs. I would suspect this is a result of the lack of flexibly combined with poor alignment + the designer not designing for the twisting and lateral loads as a result of these misalignments.
I work in the iron industry of WA is this trend mirrored elsewhere?
Has anyone seen a wheel design that has some flexibility to run with a rigid tripper and track? Maybe something like a rail bogie wheel? Obviously belt tracking needs to be considered in this system.
Best regards,
Gareth
Hello Gareth,
I can only relate to the tripper I dealt with that stockpiled Halite underground
it has a 36 inch belt, small diameter pulley wheels, and only a forward and
reverse pendant on the trolley car.
It essentially was numb dumb and stupid because it was winched with a single
1/2" wire rope that was attached to the tripper trolley and spooled to a double
drum winch at one end of the catwalk on top of the surge bin.
The entire frame of the tripper and cat walk consisted of a lattice girder using
steel beams and tubular steel to create the lattice girder from what I remember of it.
As it was both anchored to the roof line and both ends of the excavation it worked
well and is still working after 39 years.
We used to have a lot of fun with the new hires and get them seasick when three or more of
us would walk in step from one end and the entire catwalk would start bouncing.
The cable was looped through sheave pulleys along the cat walk and then fed in a direct line
to the tripper trolley where it was payed out and retrieved at the same time maintaining
tension on the wire rope and trolley at all times. ■
Re: High Capacity Trippers And Shuttles
These days in WA a lot of the big companies have banned the use of wire ropes. They are classified as a stored energy device. ■
Travelling Trippers
Originally Posted by blakeygWhat are you all seeing as far as the current design trends for high capacity trippers or shuttling heads?
What I have seen lately are stiff tracks/support frames with stiff trippers/shuttles with large flanged rail wheels either side of moving car.
What happened to the flexible designs of the past that allowed for some misalignments?
What happened to only constraining 1 wheel and allowing the other to float?
I am looking at a lot of breaking wheels and structural failures on the new designs. I would suspect this is a result of the lack of flexibly combined with poor alignment + the designer not designing for the twisting and lateral loads as a result of these misalignments.
I work in the iron industry of WA is this trend mirrored elsewhere?
Has anyone seen a wheel design that has some flexibility to run with a rigid tripper and track? Maybe something like a rail bogie wheel? Obviously belt tracking needs to be considered in this system.
Best regards,
Gareth
Originally Posted by lzaharisI can only relate to the tripper I dealt with that stockpilerd Halite underground
it has a 36 inch belt, small diameter grooved pulley wheels, and only a forward and
reverse pendant on the trolley car.
It essentially was numb dumb and stupid because it was winched with a single
1/2" wire rope that was attached to the tripper trolley and spooled to a double
drum winch at one end of the catwalk on top of the surge bin.
The entire frame of the tripper and catwalk consisted of a lattice girder using
steel beams and tubular steel to create the lattice girder from what I remember of it.
As it was both anchored to the roof line and both ends of the excavation it worked
well and is still working after 39 years.
We used to have a lot of fun with the new hires and get them seasick when three or more of
us would walk in step from one end and the entire catwalk would start bouncing.
The longer retract/payout cable was looped through three sheave pulleys along the cat walk and then fed in a direct line
to the tripper trolley where it was payed out and retrieved at the same time maintaining
controlled tension on the wire ropes and on both ends of the trolley at all times and maintaining
the alignment of the trolley at the same time with only the wire ropes.
The shorter cable was fed directly from the winch drum in a straight line to the front of the tripper trolley.
Originally Posted by blakeygThese days in WA a lot of the big companies have banned the use of wire ropes.
They are classified as a stored energy device.
Hello again Gareth,
A system like the one I described is not considered an energy storage device.
The proper term for a traveling tripper like the one I described is that it is
tension neutral because the cable tension is zero/neutral due to the sheave blocks simply
being used to guide the wire rope in one linear movement on a level plane rather
than being used to tug it with great force
The ONLY location that tension is created is at the double drum winch in a linear movement
where both cables are spooled via the sheave blocks limiting the pull to moving the
tripper trolley and the weight of the belt and ores coming across the head pulley and being
dumped in the surge bin at 450-550 tons per hour.
The trolley is simply pulled in either direction with the two wire ropes using the
opposing wire rope connected to the base of the trolley to maintain a very slow speed of travel-cheap brakes without
the trouble of brakes.
The grooved wheels on this travelling tripper act as simple stationary grooved steel wheels that move back
and forth along the top of the angle iron welded to the two lengths of tubular lattuce girder/H beam that
the tripper rides on. ■
Wheels To Go
Hello Gareth,
i do rail / wheel design of movable bulk handling machines and may say, that there're still flexible design approaches and designs that allow for misalignment and also designs strong enough to withstand operational loads during acceptable time spans. Warranty consience and solid reputation of the supplier will bring those.
However, there's two simple points as of today's situation which might counteract:
Cheap supply of wheels and related structure and poor rails / rail support + fixation + alignment (which then also comes down to cheap buy).
It is feasible for an experienced mechanical engineering firm company to design mechanically correct (i.g. with sufficient degrees of freedom) wheel support systems. This needs joints, bogie systems, perhaps fixed side / floating side design, machining of larger structural parts, in-depth calculation, nonsubstandard manufacture and so on. But: This is much more expensive than a welded beam + bolted pillow block supported wheel design with just the perpendicular basic joints and the idea that wheel flanges take care of the rest. CAPEX is the word.
Anything mechanically constrained shall draw more force than perhaps might be precalculated with a statically nondetermined structural approach. Which is in my opinion feasible at dutily determined & fixed external environment conditions. But perhaps not quite at conditions that might be met at rough and raw bulk facilities, seen rails, rail positions, alignment of wheelsets to structure and rail etc, after some years of service.
It would be great if you could share some of your failure pics + some comment, however. I for one would thank you so much.
Best regards
R. ■
Re: High Capacity Trippers And Shuttles
You may already be aware of it and it does not quite address your enquiry, though the following may be of interest:
D.E Beckley, 1983, Belt Conveyor Trippers - Design Philosophy and Techniques, Bulk Solids Handling, Volume 3, Number 4, pp 763 - 766.
Regards,
Lyle ■
Re: High Capacity Trippers And Shuttles
Hello,
Mobile machine design is not new issue, and concerned engineers are well familiar with the same. Three point in space are always in single plane i.e. a flat plane will always pass through three points irrespective of their X, Y and Z coordinates.
This is not so for 4-points. The 4 points in space will be on single flat plane if they are deliberately put on flat plane, else they will not be on single flat plane most of the time.
If the chair has 3-point (like tripod), all the three legs will be sharing determinate load all the time irrespective of unevenness in floor, and if load is at CG of 3-point (triangle), all the 3 legs will have determinate as well as (possibly) equal load. This is not so for 4-legged chair, as is known by all.
The mobile machine support system has following variants (also reference to article in Transtech publication):
1) Three point system, with 3 corner wheel (group of wheels). This is widely used for rail mounted machines and ensures determinate load on wheels.
2) Three point support system, converted to 4 corner wheel (group of wheels). This is widely used for rail mounted machines and ensures determinate load on wheels.
3) 4-point support system with, hydraulic suspension at two corners (on one rail), with pressure equalising connection between them, ensures determinate load. Not very common due to liability of maintenance and upkeep of hydraulic system. For simple ‘tripper’ engineers can also use leaf springs at the aforesaid 2-corners, but some how not in practical use, could be due to its design, procurement and time problem.
4) Four point support system, when rail vertical alignment tolerance are very close and structure twisting will remain finite for all practically expected probabilities.
The plain travelling trippers are generally made as per this. Diagonally located two corners will be resting on rails and also one other corner which is bearing heavier weight. The entire structure will sag (twist) so that the non touching wheel may touch the rail if structure is adequately flexible and may not touch the rail if structure is very rigid. The frame with some flexibility to deflect is superior. In either case occurring stress should be well below the yield stress.
As for wheel tread wear, it arises due to: A) Wheel shafts not exactly perpendicular to rail track (travel). B) Inadequate wheel load causing wheel slippage, of drive wheels every time the travel drive is started. C) Oversize / high starting torque of travel drive not matching to wheel load.
5) As for long shuttle conveyor, this can have segments having 4 corner support wheels and segments being flexibly coupled with butting (buffer) to take compressive thrust exerted by belt tension.
Regards,
Ishwar G. Mulani
Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book : Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
High Capacity Trippers and Shuttles
Dear all,
What are you all seeing as far as the current design trends for high capacity trippers or shuttling heads?
What I have seen lately are stiff tracks/support frames with stiff trippers/shuttles with large flanged rail wheels either side of moving car.
What happened to the flexible designs of the past that allowed for some misalignments?
What happened to only constraining 1 wheel and allowing the other to float?
I am looking at a lot of breaking wheels and structural failures on the new designs. I would suspect this is a result of the lack of flexibly combined with poor alignment + the designer not designing for the twisting and lateral loads as a result of these misalignments.
I work in the iron industry of WA is this trend mirrored elsewhere?
Has anyone seen a wheel design that has some flexibility to run with a rigid tripper and track? Maybe something like a rail bogie wheel? Obviously belt tracking needs to be considered in this system.
Best regards,
Gareth ■