The structure of ELEMET elevator belts is a steel carcass composed by a strong warp of steel cord with suitable elastic modulus such to reach the best compromise between low elongation and good flexibility. This characteristic makes the belt easier to be aligned than traditional steel cord elevator. Furthermore, the cable elasticity allows the use of pulleys with lower diameters, depending on the requirements of clamps and buckets.
Two regular steel wefts placed on top and bottom cover give to the belt high transversal stiffness, necessary to assure the best stability during the running; at the same time, it helps the belt for the buckets holding up highly increase cutting and tear resistance.
Due to the high quality of steel cord, it is possible to design ELEMET with very low safety factors. As some cords are broken during the punching process, we recommend to use a minimum safety factor of 10 calculated
considering the usefull belt width (see Pag. 6 - Elevator belt calculation - for more details).
However, if lower elongations are required, we suggest to increase the safety factor up to the double.
Rubber covers for elevator belts have two main functions: protection of the carcass against material and moisture aggression, assurance of the perfect bucket holding up without bolt loosening in course of time. In order to guarantee safety and longer life, under hard working conditions too, all type of rubber covers are antistatic and ozone protected.
SX - Medium temperature resistance
SX is a rubber compound assuring resistance against abrasion; it is formulated for maximum temperature of 100°C. It is not oil resistant.
BX - Superior temperature resistance
BX is the rubber cover that assures the maximum heat resistance for a rubber compound. It is designed to work at maximum temperature of 180°C. It is not oil resistant.
|Belt style N/mm||800||1000||1250||1600||2000||2250||2500||2750||3000||3200||3500|
|Drive pulley mm||500||500||630||630||630||800||800||800||800||800||800|
|Lower pulley mm||400||400||500||500||500||630||630||630||630||630||630|
|Belt style N/mm||800||1000||1250||1600||LE2000||LE2250||LE2500||LE2750||LE3000||LE3250||LE3500|
COPERTURA RESISTENTE AL CALORE SX (100 C°)
|Cover thick. mm||3+3||3+3||3+3||3+3||-||-||-||-||-||-||-|
|Belt thick. mm||11,4||11,4||12,3||12,3|
|Belt weigth mm||17,6||18,2||20,1||21,4|
COPERTURA PER ALTE TEMPERATURE BX
|Cover thick. mm||4+4||4+4||4+4||4+4||4+4||4+4||4+4||4+4||4+4||4+4||4+4|
|Belt thick. mm||13,4||13,4||14,3||14,3||15,0||15,0||15,0||15,0||15,8||15,8||15,8|
|Belt weigth mm||19,2||19,9||22,0||23,1||24,4||25,5||26,0||27,0||29,1||29,9||31,2|
Suggested take-up travel (for minimum safety factor 10)
Up to belt style 2000 kN/m ≥ 0,40 % of the centre distance
From 2250 up to 2750 kN/m ≥ 0,35 % of the centre distance
From 3000 up to 4000 kN/m ≥ 0,30 % of the centre distance
For belt style from 3000 to 4000 kN/m with special construction, please contact our Commercial Dept.
Available special constructions on demand and under technical approval.
Metal clamps for ELEMET
There is not a general purpose clamp suitable for all steel elevator belts as it must be designed in accordance with the tensile strength of the belt, the diameter and the construction of the steel cables, the pulleys diameter, the holes pattern for bucket fixation.
Although ELEMET are realized with very thin and elastic steel cables in order to minimize the effort in the joint bending area, two particulars of these clamps are fundamental for the right performances without breaking of the cords or tearing of the belt:
a) sufficient radius of curvature in order to distribute the tensions along the cords reducing the possibility of cord breaking due to steel fatigue;
b) suitable bolts distribution, steel plates robustness and clamp surface with high friction coefficient to assure perfect clamping with a minimum number of cord breaking.
elevator belts is described. Various tensions T [daN] in the belt must be taken into consideration:
1. T1=P1·H due to belt weight P1
2. T2=P2H/p due to bucket weight P2
3. T3=P3H/p due to material weight P3
Capacity Q and weight of the handled material for each bucket P3 are connected by.
If there are inconsistency between P3 and P3calc use in the calculation of T3 the greatest value between the data P3 and the value P3calc coming from the capacity calculation. An investigation on this conflict is suggested.
4. T4=DJT3/H due to friction at the loading point.
5. T5=MAX(K(T3+T4)-(T1+T2),Fv/2) to guarantee motion transmission.
The therm K(T3+T4)-(T1+T2) represents half of the minimum take-up value that must be applied. Negative values mean that buckets and belt weigth are sufficient to assure the minimum required pretension.
The maximum tension in the belt is the sum of these a.m. values T=T1+T2+t3+t4+t5. For the calculation of the minimum tensile strenght a usefull belt width Bu=B-dfnf lower than the real belt width must be considered because of the presence of the hole necessary for the bucket holding.
If at least one of these datas are unknown, we suggest to use a safety factor fs ≥ 15 in the calculation of minimum tensile strength instead of the standard safety factor (fs=12 for Eletex and fs=10 for Elemet).
So, the minimum tensile strength is CRmin= fs. Chosen a tensile strenght CR greater or equal to the here above calculated value CRm, it is possible to verify the effective safety factor fs’= .
The motor power necessary to move the belt loaded with the material must balance T3+T4 because the tensions T1 + T2 produces autocompensative effects along the whole lenght of the conveyor: .
Introducing the mechanical efficiency of the transmission and a power surplus of 20%, the minimum motor to apply to the conveyor belt must be Pm=1,2Pa/h.
P1 [kg/m] = Belt weight
P2 [kg/each] = Bucket weight
P3 [kg/each] = Material weight for each bucket
P3calc [kg/each] = Material weight of each bucket necessary to guarantee the capacity Q
Q [Ton/h] = Elevator capacity
v [m/sec] = belt speed
H [m] = Elevation
p [m] = Buckets pitch
D [m] = Lower pulley diameter
J = friction factor on the carter: generally 8, for big lump size 12
K = Friction factor on drive pulley (tipically 0,5)
Fv [kg] = Applied counterweight (including the lower pulley weigth)
T [kN/m] = Maximum belt tension
CRmin [kN/m] = Minimum tensile strength
B [mm] = Belt width
Bu [mm] = Usefull belt width
df [mm] = hole diameter
nf [mm] = hole number for each bucket
fs = Safety factor
fs’ = Effective safety factor
Pa [kW] = Theorical motor power
Pm [kW] = Minimum required motor power
h = Drive efficiency