Products - Series 820 (Page 3 of 3)

Series 820 Torque Limiter Selection

Method
Data required for Torque Limiter Selection.
•	Application details (for service factors).
•	Kilowatt and rpm of the driver.
•	Shaft details of the driving and driven equipment.

(1)

Determine the nominal torque (Nm)

Torque (Nm) = Kilowatt (Kw) x 9550 / rpm

Consideration should then be given to start torque or other special circumstances depending on the position chosen in the drive system. Choose a set torque with a suitable margin over nominal. Select the Torque Limiter which has a higher torque rating. For 820 Type 1 check pin coupling selection.

(2)	Check the Limiting Conditions:
(a)	Check hub bore capacity and speed rating.
(b)	Check the Torque Limiter dimensions such as the overall length and outside diameter.

(3)	Select and specify the appropriate drive medium or coupling.

All Autogard Series 820 units may be supplied from the factory at a pre-set torque and with the required drive medium assembled to the unit.

Model 820 Type 1 - Pin Coupling Selection Method

When selecting a Model 820 Type 1, the customer needs to confirm that the coupling is suitable for the continuous torque taking into account the duty in which the unit will be used.

(1)	Determine the nominal torque Torque (Nm) = Kilowatt (Kw) x 9550 / rpm.

(2)	Select the appropriate service factor fD as shown in Table 1 taking into account hours of operation per day and the prime mover used.

(3)	From Table 2 select the factor for the frequency of starts per hour (fS).

(4)	Determine selection torque. Selection Torque (Nm) = nominal torque x fD x fS.

(5)	Check to ensure that the coupling’s nominal torque rating exceeds the selection torque. If is does not, select the next larger torque limiter which meets this criterion.

Table 1 - Pin Coupling Service Factor (fD) (820 - Type 1 only)
	Driven machinery characteristics
Prime mover (Drive input)	Duration Service Hours/day	Steady Load	Medium impulsive	Highly impulsive
Electric, Air, Hydraulic Motors Steam Turbines (Steady input)	Intermittent 3 hrs/day max 3 - 10 over 10	0.90 1.00 1.25	1.00 1.25 1.50	1.50 1.75 2.00
Multi-cylinder I.C. Engine (Medium Impulsive input)	Intermittent 3 hrs/day max 3 - 10 over 10	1.00 1.25 1.50	1.25 1.50 1.75	1.75 2.00 2.25
Single-cylinder I.C. engine (Highly impulsive input)	Intermittent 3 hrs/day max 3 - 10 over 10	1.25 1.50 1.75	1.50 1.75 2.00	2.00 2.25 2.50

Table 2 - Pin Coupling Service Factor (fS) (820 Type 1 only)
No. of Starts per Hour	0 - 1	1 - 30	30 - 60	60 +
Factor	1.00	1.20	1.30	1.50

Notes
•	Service factors provided are for reference only. Customer experience may dictate the selection of different Service Factors.
•	For applications with excessive vibration, contact Autogard Engineering.
•	Rotating Equipment must be provided with suitable guarding or injury may result.

Ordering the 820 Series Torque Limiter

When ordering please provide the following designation

Model & Size / Type / S1 Bore / S2 Bore
Standard bore tolerance = H8 + normal fit key.

Example:
820 - 3L / 2 / S1 - 110 / S2 - 130

Refers to a Model 820 size 3L Type 2 torque limiter
S1 Bore = 110 mm S2 Bore = 130 mm
Also specify setting torque if required.

The specifications contained within this page are correct at the time of going to print. British Autogard are continually reviewing and updating the specifications on all its product range and therefore reserve the right to change any detail