Safety Knights

Great question. I know the formula for force is mass times acceleration, but I have no idea honestly how to determine that on a pallet jack handle. I'd say reach out to the manufacturer to see if they have that info, but other than that, you'd probably have to get an ergonomist or someone else qualified to determine that for you.

There'd be a lot of variables in that, too, such as the maintenance/lubrication/etc. of the handle that would affect force, so I'm not sure the manufacturer would be able to get you an exact number on that.

Overall, 5 lbs. isn't a lot, so I'd keep them off of it until you can verify otherwise.

Like Drew said, 5 lbs isn't much and it won't take much to go over that, so I'd keep them off the pallet jack.

If you really wanted to know, one way would be to use a spring scale. Simply attach one end to the handle and manipulate it to see how much force is required to move it.

The best tool I am aware of would be a force gauge used in ergonomics (also called a push/pull gauge). You would need to attach the gauge to the handle and measure forces while you operate the rider.

The way I read your question, you’re talking about a rider so the operator just uses buttons/controls to do the lifting and the only major movement they’re doing is steering? As Drew said, 5 pounds is a pretty low limit; if all you’re doing the steering, you might be under it. Without splitting hairs too much, lifting and push/pull are potentially two different things, so really understanding the medical provider’s restriction is important. Either way, I think this one will be challenging to have the operator perform normal duties with restrictions. Do you have some paperwork back logs that need attention? 6S that needs to be refreshed?

I would call this a "paper-clip" counter injury.

I agree with everyone below. Measuring the force is tricky but I think you could really come close with any of the methods mentioned below.

But I agree with Tim, Patrick, and Drew why bother? In 42 years of WC and HR work I do not ever remember seeing many restrictions below 10 pounds (I may have seen a few but not many!). At 5 pounds I think the doctor is sending you a message the person cannot do very much. If your intention is to get the employee to do whatever they need to do to improve I will tell you how I came up with the name "paper-clip" injury.

My former company had a strict policy that we wanted people back to work post-injury no matter what it took! We made sure every medical provider knew we would accommodate any restriction short of the employee be flat on their back with an "IV" in their arm. We went to great lengths sometimes to do this. I remember once an electrician came to me with a note post elbow surgery that said she could not drive. With a smile she said, "I live 75 miles from here, and my husband has a fulltime job in the other direction so he cannot drive me! I guess I will just be off work and you will pay me comp!" The injury was dubious as work-related and were contesting it as compensable , but she was right in the short-term she was right, we would have to pay her comp till we went the IME and probably court route and she stayed home.
To her surprise I picked up the phone and called a local cab company. I asked them if they could send a cab out every day to a home early in the morning every day, and then return the person in the afternoon. It would be 75 miles one-way. They said they could but it would be costly. I said how much and they said, $300 a day (this was 15 years ago). So I gave them my credit card number and said let's do it!
I looked at the female electrician and said, be ready at 6:00 AM a cab will pick you up and the will take you back home! As my momma use to say,

5 lbs. is real close to no lifting. Its almost pointless to write that. Common sense of the tasks would be enough for me to restrict them from operating. What could happen is my determining factor. What if it was a sudden need to stop, or turn? Don't fall victim to normal operating conditions not including everyday hazards that need to be dealt with. Restrictions mean liability and potential to aggravate. Safety has a responsibility to default protecting the worker. "What if" over rides a Dr. saying 5 lb restrictions.