Track drive negative brake calcualtion

The output torque is the pressure x displacement of the motor.

The static torque is the torque required at the shaft to start the motor turning.

You will need a brake to hold the load.

Thanks, but the there is brake built into the unit. This uses springs to hold the load and pressure to release. The question is, the brake can hold 350 Nm but the load could be has high as 7500Nm.

Is the brake torque multiplied by the gearbox ratio? 350 * 25.2 = 8820 Nm.

OK, sorry. I see your point.

The winch has a gearbox on it, hence the ratio.

The external load driven through the gearbox will reduce the torque.

Point 3 is saying that the brake holding torque is between 1.6 and 1.8 x the input torque. If you then divide this by your gearbox ratio, you will get your number.

Pretty much as you have it, depending on the ratio that you use.

The 1.6 - 1.8 value is the 60 - 80% safety margin to protect against impulse loading and stopping the load when the brake is applied. If the safety margin is too high, the brake will decelerate the load too quickly and cause other issues like buckling cylinder rods and bad stuff like that.

8820Nm as an external load, driven through the gearbox, will produce 350Nm at the motor shaft. That's too high, the load will likely creep down as it's too close to the brake holding force. You need to select a higher ratio to reduce the torque if you are going to produce an input torque of 8820Nm.

You need to match the input load with the ratio, so that T1 x 1.6 is less than or equal to 350 and T1 x 1.8 is more than 350.

Even if you use the 39.2 ratio, that will give 360Nm at T1 x 1.6. That will cause the brake to be too sharp / aggressive.

You need to select a ratio that you can use, allowing for the power available and therefore the speed of the winch. Once you have that, you can identify the values of T1 that will put you in the sweet spot with the brake.

Using the 39.2 ratio, as it's the closest, T1 can be 8575Nm to be right on 350Nm with the 1.6 margin.

If you want to go the other way and use more margin and have the brake working at 1.8 x T1, then T1 needs to be 7622Nm