Newbie Question - Autofill a field based on previous record in Access

[isafu001]

Hi, first of all, I am very new to Access.

I'm trying to track fuel consumption for heavy machinery units. 

Apologies for the scribble but the table looks like this: 

I need HMstartU to retrieve the last known value of HMendU automatically, for all of the different machinery. 

Any help or even just pointing me on what to search for would be appreciated, thank you! 

[#2]

Use a subquery
See if you can adapt the approach in this article by Allen Browne.
http://allenbrowne.com/subquery-01.html#AnotherRecord

[#3]

@isafu001 

there is a similar thread here:

Solved - Update blank values | Access World Forums (access-programmers.co.uk)

here is a demo that uses Data Macro.

open the table (Usage) and enter some data (same as in your posted snapshot)