Brass plate in Jockey wheel assembly

Vauxfiat

Hi all,

          I am looking for a bit of advice if possible. I have just had to replace the jockey wheel on my caravan and found that the brass plate within the securing bolt mech keeps coming off. I put the plate back in but it stopped me from installing the
jockey wheel shaft. I have since taken it off and my jockey wheel mechanism fits perfectly.What I am asking is how important is this brass plate?

Thanks in advance

Greg