Property, plant, and equipment consists of the following:


	March 31, 2021		September 30, 2020
Machinery and equipment	$	376,831	$	357,650
Rental equipment	236,469		221,953
Land and buildings	69,541		70,245
Construction in process	53,324		48,325
	736,165		698,173
Less: accumulated depreciation	(364,297)		(333,712)
	$	371,868	$	364,461

The Company entered into secured financing agreements that require providing a security interest in specified equipment. As of March 31, 2021 and September 30, 2020, the gross and net amounts of those assets are as follows:


	March 31, 2021				September 30, 2020
	Gross		Net		Gross		Net
Machinery and equipment	$	68,578	$	55,023	$	63,305	$	52,620
Construction in process	15,140		15,140		8,098		8,098
	$	83,718	$	70,163	$	71,403	$	60,718

Depreciation expense and maintenance and repairs expense for the three and six months ended March 31, 2021 and 2020 were as follows:


	Three Months Ended March 31,				Six Months Ended March 31,
	2021		2020		2021		2020
Depreciation expense	$	18,769	$	18,185	$	37,280	$	35,488
Maintenance and repair expense	4,754		5,249		9,962		11,314